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VMworld 2018

Another year another VMworld. I’ve got a few sessions I will be presenting:

 

HCI1473BU The vSAN I/O Path Deconstructed: A Deep Dive into the Internals of vSAN
??? Mystery Session: 7/27 at 3:30PM
HCI1769BU We Got You Covered: Top Operational Tips from vSAN Support Insight
HCI3331BU Better Storage Utilization with Space Reclamation/UNMAP

 

The vSAN I/O Path Deconstructed is an interesting inside look at the IO path of vSAN and the reasoning behind it.

We Got You Covered: Top Operational Tips from vSAN Support Insight shows off the phone home capabilities of vSAN and can help address your questions about what and how this data is used. We are also going to discuss how you can leverage similar views of performance as GSS and engineering to identify how to get the most out of vSAN.

HCI3331BU is a session that has been years in the making for me. “Where did my space go” is a question I get often. We will explain where that missing PB of storage went and how to reclaim it. The savings from implementing UNMAP should be able to fund your next VMworld trip!

Lastly, I’ve got a mystery session that should be unveiled later. Follow me on Twitter @Lost_Signal, and I’ll talk about what it will be when the time comes.

Pete and I will be recording for the vSpeakingPodcast Podcast LIVE! At the HCI Zone (Found near the VMware booth). We’ve got some new guests as well as some favorites lined up.

vSAN Sizing and RVtools Tips

VMware has released a new vSAN sizing tool!

Some guidance for the tool has been included on how to use it are in the design and sizing guide on StorageHub.

A lot of partners like using RVtools (A great way to make a simple capture of an inventory, health, and configuration) as a means to collect storage capacity information, as well as a snapshot of compute allocations.

  • If you have a large number of powered off VM’s have a serious discussion if they will all be started or needed at any time. If not, consider excluding them from compute sizing.
  • Use the health tab and look for Zombie VM’s and see if these cold VM’s can be deleted or migrated out.
  • Look for open snapshots, and see if these need to be collapsed (which can save space).
  • Be aware of the difference in the two storage metrics (allocated vs. consumed MB). If you intend to keep using thin provisioning, you do not need to size for all of the allocated. In the video, this is a significant capacity difference.
  • If the existing solution has VM’s tied to storage demands (Storage management VMs, VSA’s) that will be deprecated by vSAN be sure to exclude them.
  • Have a serious discussion on if the vCPU to physical core ratio is “working” or if they see performance issues. I’ve seen both people be too conservative (1:1 in test dev) and too aggressive (20:1 for databases!). You can see the existing ratio’s on the host tab.
  • Pay attention to CPU generations. Vintage Xeon 5500 will be crushed clock for clock by new EPYC processors.
  • Realize you can change the CPU configuration (Cluster advanced options). Some people may want to optimize their CPU model for licensing (commonly 16 core for windows, or possibly lower core but higher clock for Oracle). You can change these assumptions.
  • Be sure to check out the health tab, and look through the host configs. Make sure NTP is set up on hosts! Use this as an opportunity to see if the existing environment is even healthy.

Have any more tips and tricks? Check out the comments section below!

 

 

 

Where did my host go….

I was reading Bob Plankers colorful complaints about his Intel X710/XL710/X722/XXV710 family of NICs and figured I’d do some digging and ask around on people I know who have them as well as summarize some things I learned from using them as a customer.

A few observations:

  • These problems are not specific to vSphere. People running Linux and Windows on bare metal ran into these issues
  • While a lot has been focused on the LRO/TSO issue, there is another separate issue tied to LLDP and duplicate mac addresses being created.

First Issue LRO/TSO

This KB Sums up the issue quite well by pointing out that these features can cause PSODs. Checking with some friends who used to be able to reproduce this at the drop of a hat the newest driver/firmware is a lot more stable in this regard, but it can still happen. Some people are leaving these disabled to stay safe, while others are hungry for the small CPU gains these features deliver.   How do I remediate it? Beyond manually setting it on the hosts Jase Mccarty has a great script that will do this in bulk for a cluster.

Next up: The case of the disappearing host!

The common symptom is that management on a host will cease to function (Pings will drop) and the host will disappear from vCenter. Sometimes something more catastrophic happens (HA triggers, host isolation is triggered, storage or vMotion fails). If you pay attention closely to LogInsight, you will see your switches are reporting Mac Address Flapping (You are sending your switches syslog into LogInsight, RIGHT?!?)

Sow what’s going on here?

 

How is VMK0 special

This goes back to the special behavior for VMK0 where it steals the mac address from a physical port. This is handy for new cluster setups where people know the MAC addresses from the OEM providing them before delivery being able to put this in their DHCP reservations and get started without needing to physically touch the hosts to know which one is which etc.

Why is this card special?

This card is unique in that there is a special LLDP agent that runs on the card and intercepts LLDP packets.  Previously I associated LLDP with simply sending information on what’s plugged in where (which is why you should turn it on for send/receive with your VDS). In this case, though the LLDP agent will also update where a MAC is located.

Why together does this happen?

The challenge comes when VMK0 moves to a different physical switch port and tries to move the MAC address with it. You get a fun ARP battle between the LLDP agent of the physical port and the VMK0 that is behind a different physical port. A good old fashioned duplicate MAC entry ARP battle ensues, and this is going to manifest itself as a host going offline completely, or flipping back and forth based on the update hold-down interval on the switch. (Side note, any real networking people feel free to correct me on my terminology here I dropped out of my CCNA class in 2008).

Why did I loose more than management (or what am I doing wrong!)?

Given most people use VMK0 for management by vCenter (and for non-VSAN clusters HA heartbeats happen here) this can have a lot of interesting behaviors like loss of management, host isolation response being triggered. This is another great reminder of why you should use datastore heart beating, or VSAN which will not depend on VMK0 for heartbeats.

Also if you are running EVERYTHING on VMK0 (Storage vMotion) which is NOT a recommended practice (isolate storage and vMotion networks!) you could see all of the virtual machines crash and other fun things.

Workarounds?

So there are a few ways to possibly work around this.

  1. You could simply avoid using VMK0 with this card. Either disconnecting it and using a new VMK4 or so forth for whatever it was being used for. This is simple, it’s easy (outside of disconnecting and reconnecting hosts) and doesn’t require you touch the network beyond having one extra IP on the management network to make it easier.
  2. You could change the mac address manually to something in the random VMware MAC address space (Need to clarify if this is supported, but it’s simple enough and avoids this issue). Note that the MAC would be set back if you ever remote and recreate VMK0.
  3. If you trust your networking team, you could try asking they hardcode the MAC address to specific ports in the CAM tables of the switch. I would look at this only as a last resort if operationally you can’t physically change anything on the hosts but need an extreme workaround
  4. *EDIT* It looks like running LACP across the origional physical port and another port will work around the issue. The switch isn’t going to care where the frame comes from, and so this should reduce or ignore the chance of an arp fight. Balancing for VMK0 across physical ports will not be great, but as long as it is is management only you will likely not care too much. (Thanks to Simon for this discussion).
  5. *EDIT* Try putting VMK0 on a tagged NON-Native VLAN. It can’t get in a fight with the LLDP agent for the MAC address if it’s on a completely different broadcast domain (Thanks to Broc Yanda for this idea).

What else is going on that I don’t know about vSphere Networking?

This week I also learned about shadow vmnics.

 

 

Tango Eagle Bravo

*Coming to a vSAN support call near you*

“Sir, It looks like Tango Eagle Bravo is the problem”.

 

Why does this sound like something out of a Nickolas Cage movie? Let me explain.

Today vSAN out of the box can phone home Performance, Configuration, and health telemetry to support and engineering using the vSAN Support Insight functionality. Note this phone home data builds an obfuscation map by default so that hostnames, virtual machine names, and network information are not exposed in the phone home. By using your vCenter UUID support and engineering can further drill into the environment and diagnose many common issues without necessarily needing a full manual log collection.

If you want to inspect a sample of what it looks like you can read through this JSON file here.

What happens when Support finds an issue and explains the secret code name for the Virtual Machine or host that is the problem? Where do you find a secret decoder ring to make sense of this?

In the vSphere Web Client, navigate to the vSAN Cluster > Configure > vSAN > Health and Performance > Online Health Check. Click on the Download Obfuscation Map

In the CLI on the VCSA?

  1. SSH into vCenter Server Appliance.
  2. Run command: cd /var/log/vmware/vsan-health/
  3. The obfuscation mapping file is <uuid>_obfuscationTableForHuman.json.gz.
  • Windows Environment:
    1. Login to Windows vCenter Server machine.
    2. Open C:\Program Files\VMware\vCenter Server\logs\vsan-health
    3. The obfuscation mapping file is <uuid>_obfuscationTableForHuman.json.gz.

What if you are not phoning home CEIP data? 

It’s time to turn it on. It’s less information than a normal log collection would include, and by having it phone home regularly you are in a better situation to get faster support should you need it. For setup and network requirements check out this storage hub section.

What happens if you do not have compliance needs to speak in code, and would rather VMware just have direct access to your Virtual machine and Hostnames? You can email, or upload and attach it to the ticket. Support can bind this in vSAN Support Insight, but it will expire in 7 days.

 

 

What is in the obfuscation map?

Here is a sample.map file.

Protected: The performance problem is in another castle

This content is password protected. To view it please enter your password below:

So you are thinking about taking an offer… What do you need to know?

It’s a new year and I’m sure some of you had resolutions to look at a new job. As budgets “Unfreeze” new jobs are opening.

This post has some history. Previous to coming to VMware I worked for an IT consultancy and used to at one time be a hiring manager. It was always interesting seeing why people chose to stay, leave, or join our shop. Even when people left, I heard about their future moves by being a common reference used for the previous manager. On top of this new hires would often ask me a million different questions about a job trying to compare the old company with the new company regarding benefits (both compensation and non-compensation related).

From this, I’ve amassed an interesting list of:

1. Compensation that often is overlooked
2. Things you want to know about a job before you take it for the quality of life reasons
3. How to know if the grass is greener (or not) on the other side

While this list isn’t something you would send in whole to a recruiter, it’s information that through various sources you might want to try to understand before making a jump to a new job. The first half is Job questions; the second half is compensation questions.

 

The Job Questions…

What’s the team/dept/companies view on Training?

If they don’t have a training programme or allow time for training/skills improvement that could be a red flag.

Why is the position open?

Growth, backfill, etc. This is the reverse of “why are you looking to leave your last job?”. If it’s the 3rd time, they tried to fill a roll something may be off…

What are the expected hours? What are the exceptions, holidays, etc.?

I once worked an outage till 4 AM then was expected to walk into the office by 8:30 AM I was happy to leave that place. School districts might do four day work weeks in the summer; some oil/gas companies do 4 x 10’s or other weird schedules. Occasionally I have to take calls early or late (to deal with people in EMEA, ANZ, etc.).

Are there SLA’s in place?

What is expected of your team, and are they equipped to meet it?

What is the annual IT/Department budget?

Whats the budget for your group look like? What projects have been funded as well as what is planning on being funded can be a proxy for this question. You don’t want to walk into a shop with 8-year-old systems and no budget for replacement.

Who determines the IT budget?

What’s the process, who are the actors involved?

What’s the company’s position on open/capex IT spend?

Lease vs. Buy. Are they balanced, or for financial reporting reasons (ROIC) are they 100% one or the other if possible.

Are they cloud (friendly, neutral, hostile)?

What are they using for cloud now, and what are they planning on migrating?

What does your current infrastructure look like?

Shiney brand new VxRAIL/UCP-HC Cluster, or 200 Physical servers running Windows 2000? How bad is the technical debt? What/where are the datacenters, who are the providers, what is the networking, (WAN, and edge/campus gear). What storage vendors and hypervisors are in play.

What is the spread of the tasks expected and are they reasonable?

There’s nothing like being hired to be a data center architect and discovering that fixing printers is in your responsibilities. Skill growth requires you focus on things that matter. Also, if managers see you fixing printers or doing other lower end work, they tend to mentally associate what you should be paid with the bottom 10% rather than the top 10% valuable work.

What Services are outsourced?

Does someone manage printers, the WAN circuits, the storage, backups, the DR, etc.? Beware shops that don’t believe in outsourcing anything as they tend to view in-house labor as a “free” commodity.

What are they doing for DR? 

This question is a mix of what is their plan, and what is a reality. How often is it tested? Do they hit the SRM failover button once a quarter, or do they have an out of date binder?

What is the targeted refresh cycle for Network/Servers/Storage?

Do they run stuff five years, ten years? Do they run gear beyond its natural life, or beyond support agreements?

What is the maintenance schedule?
Do they patch at all, is there automation in patching.
What Compliance do they have?
PCI/HITECH/etc.

The Team Questions

Who will be the manager? Can I meet them? – It’s a red flag if you can not meet your line manager. You will want to know the person who will assess your performance, impact your bonus, assign you good (or bad) projects, etc…

What is your biggest daily/weekly frustration?

Key things to note is if this is something you can stand, or if this is something that’s fixable. Bonus points if you bring unique skills, or you will be working on a project to fix it. “Our Fibre Channel network is slow, but the HCI project you will be on should fix that!”

Ask about how success is measured?

Is there a forced Stack rank? Are there general metrics that you target (uptime, on-time delivery of projects?).

Who is on the team? Can I meet them? Knowing who you work with is crucial. Are they talented, Friendly, cooperative?

How does the team communicate? Are there daily meetings, do they use Slack, do they just use email, is everyone in the same building? What percentage of the teamwork remotely?

How is documentation handled? (Well documented Wiki, vs. the last guy, torched Jira on the way out and you will be guessing passwords).

What are the platforms and Vendors?  Are you a CCIE and it’s an all Juniper shop? Don’t be scared! The key is knowing what area’s you will need training.

What is the new employee onboarding process?  – Will it be two days of well-orchestrated events, or will you still be waiting for a phone and computer 30 days later?

What are expectations for the first 90, 180, 365 days? Is there a project, or milestone or education path they need you to have accomplished. How long do they expect you to fit into the shoes?

What is the cross coverage?

Is there only one person who knows how to restore from backup? Is there cross training? This can be bad if you want to go on vacation…

What is the upward mobility? 

What are the expectations for moving up in title, rank, role/responsibility? Are there defined elements to your career path and claim or will you be “IT Dude” until “Head IT Dude” retires?

*What about the Company*

What’s the companies roadmap?

If they don’t know where they want to go then it’s going to difficult to help steer them there.

What is the YoY growth? Is the company growing, or is it holding on for life support? Some industries are cyclical (Oil/Gas) some are past their prime (Sun Microsystems was a different company to work for in 1994, and 2001).

How many Employees are at the company? At a five man company, you might have to put toner in the printer. At IBM you likely will not know that person name. Some people like large companies, some like smaller. There are pros and cons to both.

Is the company profitable under GAAP? Companies sometimes do crazy things like claim they are profitable if you exclude employee compensation. If a company is a tech startup growing 100% year over year, don’t expect this one to be true, but if it’s a mature public company, this is something you can look up.

If not, what is the timeline or pathway towards profitability? If it’s a startup, it may be planning on exiting soon, or taking more VC and growing to the moon. Both have their risks, make sure you understand them. What is the runway (how long at the current burn rate will they survive)?

What is the companies competitive advantage? Is it low cost? Is it Intellectual property? Is it market saturation/penetration? This can shed some light on how the company operates. A ruthless lean manufacturing company might give employee’s 8-year-old laptops because they are cheap on capital spending.

What is the biggest roadblock to scaling the company?

Is it sales, marketing, operations, R&D?

What challenges does the company have at the moment? What do you foresee coming?

This can be quite telling; it can show that they’ve taken the time to identify and address challenges. Identifying key competitors here can help quite a bit.

Compensation Questions

1099 or W-2 (US). Contractor? The contractor who’s a W-2 of the contracting company? Full-time employee of end customer? LOTS of ways to chop this. There are tax implications of being 1099. Note, there are potential issues with being a 1099 as a tech worker if you are treated like a full-time employee.

Pay Cycle – You shouldn’t be living paycheck to paycheck, but knowing the cycle makes sense if your rolling from a weekly to a monthly you may need to move some things around to handle the change in cash flow.

Salary Base and it’s growth – can it grow? Is there an org chart with clear steps to moving up and getting bumps in pay? Does everyone get 1% raises and stagnate till they leave? A company that hasn’t given raises in 5 years has given everyone a pay cut.

OTE Bonus. Cash value or is it a multiplier based on base pay? Tied to metrics or your boss and directors random fancy? (This isn’t that bad, but you need to know who decides it). While there is an “On Target Earnings” nothing stops you from getting over 100%. The biggest way to see how real this is is to check with GlassDoor and existing employees who’ve been there 4-5 years. Sometimes a bonus is real; sometimes they are “Virtual”. For bonus how often is it paid out, and will they pro-rate a partial bonus for a new employee joining mid-cycle?  I once had a co-worker leave for a job that he thought made 10% more but he forgot to ask about if they had a bonus. At the end of the year, he learned they didn’t have them (or raises) and discovered he didn’t make more money.

Insurance – PPO/HSA/HMO/EPO/POS all have different issues. What’s in network vs. out of network? Also Dental and Insurance. What about medications?  Eyecare health insurance is a scam/pre-payment program. Use EyebuyDirrect or some online place to buy glasses, or max our HSA and get LASIK if you can. Reddit has a good thread explaining the difference here and how to compare.

Education

School, College, Certifications, Classes. – Do they pay for certification tests, if so how many attempts? The key one to test the seriousness of this is to ask others in the department what they have spent in the past year.

Conferences – Tacking onto certifications do they pay for VMworld? Do they cover travel and hotels? Are you banned from events in Vegas even if they are a lower cost than San Francisco? (not uncommon in SLED).

Sabbatical In our company you can apply for 3-month transfers to wildly different jobs to learn about how that role functions? You can do a 1-week education track (take education in something unrelated).

Stock and Investment Compensation

RSU (Restricted Stock Units)’s – If you keep getting these every year on a standard 2-5 (Depends on company and grant window) year vestment schedule, you eventually end up with a rather nice kicker. This also is nice if your stock doubles within a given year (Well except for capital gains). The longer you stay, the stickier these become, and the more a company likes you, the more they will give you to “handcuff” you to the company. The more a company wants you to stay the more you get these. A decent 6 figure pile of this is nice and can be used in leverage with a company who wants to poach on you why they better give you a bigger base (or a bigger pile of them!).

Stock Options – Inversely if you work for a startup, you might get stock options. These are a LONG shot gambling game (like 2% pay off), but I know some guys who their stock is trading in the 30’s and their options were in the $2 range so assuming they make it to lockout I expect to get a call to hang out on their yacht. Personally, there are so many options to screw the employee like clawbacks/ratchet clauses I don’t put much faith in these.  https://tldroptions.io

ESPP – Buy stock at a discount (See above comments). Note these are bought at a 10-15% discount based on the beginning or ending window (Whichever is lower) so its a game of heads I win, tails you lose against the market and can pay pretty well (or just be a nice couple grand of cash). I’ve had windows where I made 15%, sometimes I’ve made 115%. These are structured where you make money no matter once but read the fine print.

ESOP – The weird retirement type cousin of ESPP. I hear these are more common overseas.

Flexibility in work

Paternity leave – Some places do partial pay, some to maternal OR paternal, and some do maternal only AFTER you burn out your PTO. Note maternity, paternity, and adoption leave may have different rules. I’ve got a family member whose company policy is six months. Wife is a pediatrician at a children’s hospital. She gets Zero. This is all over the place in the US.

Vacation – My first job I had zero vacation for the first year. Note some companies this is more negotiable than salary; sometimes it’s less. Are Sick days different? Do you need a doctor note? Are there back out times for vacation (VMworld I’m pretty sure is a non-starter in my current role). Do they make you take a vacation for conferences (Yes I’ve seen this a lot sadly…)

Flex Time/Overtime pay – Can you turn overtime into time off? If you come in early can you leave early? Do you get paid for overtime (even if your an exempt employee some places will still pay if approved)? Does the company miscategorize helpdesk as exempt or other questionable legal practices?

Commute Costs – Company Car, parking pass, bus pass, toll pass? What’s the non-reimbursed depreciation? What is the $ per mile they allow for trips to the datacenter? Do you get a car allowance (EMEA this is more common)?

Work from home/anywhere Can I just leave town on Wed/Thursday and go to a beach house to finish working out the week? There are HUGE costs savings to working from home, but do pay attention if you need to supply your desk, chairs, monitors, etc.

Expense
Do they let you do your booking, do they require a corporate credit card (no points can be brutal, to the point of $20-30K easily for some people in compensation) Can you expense travel lounges on long flights. Can you expense more than $15 for lunch with a customer? Using Lift instead of downtown and airport parking has cut my mileage to non-existent for my car.

Travel

Travel Points and status – Traveling for work a lot adds up. Note this is a NON-taxable (Weird exclusion). So when traveling, I can get hotel points and airline points. With Southwest, I have a companion pass (My wife flies free with me), and with Marriot, I get free cocktails and appetizers in the afternoon and breakfast in the morning in the executive lounge. I get free upgrades with Marriot when traveling so that $150 small room can turn into a 40th-floor suite sometimes.
Travel Policy – Do they make you fly 18 hours, five hops to save $100?

Do they put you in first class if the flight is over 4 hours?
Do you stay in the Motel 8 and have to share a room (or PAY for your spouse’s 1/2 of the room if they happen to travel with you!). Do they make you fly in the morning you are presenting when it’s 12 times zones away, or do they put you up in the hotel for the weekend to adjust to the time zone, and be a tourist for the weekend?

Team Offsite, outings, parties, etc. – Got a team offsite and can you expense going snowmobiling or something cool? Beer bash for finishing release? If you are on campus are there free movie nights and other things. Does the boss cover happy hour on Friday?

Retirement stuff

401K – What’s the match? Is it partial? Does it take a while to get vested? What can you invest in? Are the default options all garbage or can you keep fees low and put money into low fee index?

401A – Like a 401K match but you don’t have to put money in, they just put x% of your salary. Common in Education and non-profits.
457(b) – Can withdraw from it without early penalty if you no longer work for the said employer. This one carries risks if the employer goes insolvent.
403B – A lower overhead 401K plan with no match. Common in Education and non-profits.

Pension – These do exist in a few places still in the US. More common overseas.

MISC.

Equipment allowance. My wife spends money on books of stethoscopes. Some people can expense screens, laptops, mice. We have vending machines for phone chargers, mice, etc. around our offices.

Telecom – Will they cover your cell phone or data plan? Did they buy you a pager to get out of paying your cell phone bill (I had one of these in 2008)?

Gym reimbursement  – Do they pay for Gym memberships.

ESXI 6.5 Patch 2 – vSAN Support Insight!

ESXi 6.5 Patch 2 is out, and with it comes a product improvement that I’ve been excited about for quite some time. The KB for what’s new can be found here.

Three storage improvements came out with this release.

  • vSAN Support Insight (including a dedicated customer bulletin with more details on this feature)
  • Adaptive resynchronization (Previously released for 6.0) – Adaptive Resync adjusts the bandwidth share allocated to Resync I/O to minimize impact to client I/O. With this feature, Resync speed will adaptively adjust during off peak and high peak I/O cycles. During off-peak cycles Resync will speed up and during high peak cycles Resync will slow down. This ensures Resync continue to make progress while minimizing impact to the client I/O.
  • Multipath support for SAS systems“vSAN now enables multiple redundant paths from server to storage with no setup required, when used with a supported multipath driver. An example of such a system is HPE Synergy.”

vSAN support insight is revolutionary in it’s ability to change the support experiance, accelerate product improvements. Support for vSphere has typically revolved around a predictable script. You call in, and if your issue isn’t easily triagable you may need to export logs. This process has some challenges because:

1. It takes time to pull logs and upload them.

2. If the issue your cluster has impacts avalability to the logs this can drag out getting a resolution.

3. Additional Logs may be needed to compare before/after with the issue.

On the support side of things, the inital call often begins with you trying to articulate your issue, describe your enviroment and any releavent details. The support staff essentailly being “blind” on that initial call until you can describe enough of the enviroment, push logs, or setup a webex/remote sessions to show the issue.

vSAN Support Insight helps with these challenges by automatically pushing configuration, health, and performance telemtry to VMware. Removing these delays is critical to improving support outcomes.This phone home data set also provides a framework for future product improvements, future support enhancements, and better cross corelation of issues for engineering.

Blog
blogs.vmware.co…upport-insight/

Video
storagehub.vmwa…-demonstration/

StorageHub Documentation
storagehub.vmwa…support-insight

HBA all the way! (and what is this HBA 330+ thing?!?)

Duncan wrote a great blog summarizing why HBA’s are a better choice over RAID controllers. Looking back we’ve seen a shift with some of our OEM’s to even go so far as to have their ready nodes always configured for HBA controllers due to their simplicity, lower cost, and fast performance.

One question that has come up recently is “What is the HBA 330+?”. Dell customers may have noticed that the HBA 330 became the default option on their 13th generation ReadyNodes some time ago. On Dell 14th generation quotes show up with a “+” added to the card causing some concern that maybe this device is not the same one certified. Upon consulting with the vSAN ReadyLabs it seems this card has the exact same PCI ID, and is, in fact, the exact same HBA. Only minor cabling changes made that in no way impact it’s recommended driver or firmware or certification status. This is currently the ONLY certified option for Dell 14G ReadyNode servers and I expect it to likely stay that way until NVMe replaces SCSI for customers.

Going forward I expect NVMe to increasingly replace SAS/SATA, and in this case,  we will see a mixture of direct PCI-Express connections, or connections through a PCI-E crossbar. All NVMe ready nodes I’ve seen tested are showing that replacing the HBA  leads to lower latency, less CPU overhead, and consistent outcomes.

 

 

vSAN Deduplication and Compression Tips!

I’ve been getting some questions lately and here are a few quick thoughts on getting the most out of this feature.

If you do not see deduplication or compression at all:

  1. See if the object space reservation policy has been set to above zero, as this reservation will effectively disable the benefits of deduplication for the virtual machine.
  2. Do not forget that swap is by default set to 100% but can be changed.
  3. If a legacy client or provisioning command is used that specifies “thick” or “Eager Zero Thick” this will override the OSR 100%. To fix this, you can reapply the policy. William Lam has a great blog post with some scripts on how to identify and resolve this.
  4. Make sure data is being written to the capacity tier. If you just provisioned 3-4 VM’s they may still be in the write buffer. We do not waste CPU or latency deduplicating or compressing data that may not have a long lifespan. If you only provisioned 10 VM’s that are 8GB each it’s quite possible that they have not destaged yet. If you are doing testing clone a lot of VM’s (I tend to create 200 or more) so you can force the destage to happen.

Performance anomalies (and why!) when testing vSAN’s deduplication and compression.

I’ve always felt that it’s incredibly hard to performance test deduplication and compression features, as real-world data has a mix of compressibility, and duplicate blocks and some notes I’ve seen from testing. Note: these anomalies often happen on other storage systems with these features and highlight the difficulty in testing these features.

  • Testing 100% duplicate data tends to make reads and writes better than a baseline of the feature off as you avoid any bottleneck on the destage from cache process, and the tiny amount of data will end up in a DRAM cache.
  • Testing data that compresses poorly on vSAN will show the little impact to read performance as vSAN will write the data fully hydrated to avoid any CPU or latency overhead in decompression (not that LZ4 isn’t a fast algorithm, to begin with).
  • Write throughput and IOPS for bursts that do not start to fill up the cache show little overhead. This is true, as the data is written non-compacted to reduce latency

These quirks stick out in synthetic testing, and why I recommend reading the space efficiencies guide for guidance on using this and other features.

New and noteworthy vSAN KB’s worth a read.

While vSAN Health Checks are constantly expanding, it’s still worth keeping up with the new KB’s to see what’s going on and if there are any issues you need to consider.

Here’s a few KB’s worth a read. 

vSAN 2017 Quarterly Advisory for Q2

This article includes links to important bug fixes in recent patch releases, outstanding issues, known workarounds and other informational articles.

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File services support by NetApp ONTAP Select 9.2 for VMware vSAN datastores

This article provides information about NetApp’s ONTAP Select solution that offers file services on VMware vSAN datastore.

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Setting up active-passive dual pathing with vSAN and vSphere

This article explains setting up active-passive dual pathing with vSAN and vSphere. This one is a bit interesting as it includes some information on the superiority of native drivers in handling internal duel path SAS fabrics in managing failover and failback.

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Understanding vSAN memory consumption in ESXi 6.5.0d/ 6.0 U3 and later

This article provides information about memory consumption in the latest version of vSAN 6.2 (ESXi 6.0 Update 3 and later) and vSAN 6.6 (ESXi 6.5.0d and later) and a provides example scenarios.

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Duplicate SCSI IDs causing SATA drives in drive bay #1 to go missing from ESXi when running the nhpsa driver on Gen 9 HPE Synergy compute modules, HPE ProLiant DL-series servers that include a SAS expander

This document highlights an issue observed when using Gen 9 HPE Synergy compute modules or HPE ProLiant DL-series servers with ESXi 6.5, the native nhpsa driver and SATA drives. There’s a workaround for now (Leave drive bay 1 empty, or use a SAS device for it).

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vSAN 6.6 Ondisk upgrade to version 5 fails with the error “A general system error occurred: Unable to complete Sysinfo operation…”

This is resolved by going to 6.6.1 and performing an update while using the re-sync throttle function. Note, if your on vSAN 6.6 you REALLY want to get to vSAN 6.6.1. Huge performance improvements, beyond bug fixes like this.

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