VMware

This week I had the pleasure to talk to John Nicholson who works for one of our partners (Synchronet out of Houston). John has been involved with various Virtual SAN implementations and designs and I felt that it would make for an interesting conversation. John in my opinion is a true datacenter architect, he has a good understanding of all aspects and definitely has a lot of experience with different storage platforms (both traditional and hyper-converged). Something I did not mention during our conversation, but the answers John was giving me to some of the questions were most definitely VCDX-level. (If you can find the time, do it John :-)) Below is John’s bio, make sure to follow him on twitter:

John Nicholson vExpert (2013-2015) is the manager of client services for Synchronet.  He oversees the professional services who deploy cutting edge virtualization, VDI, and storage solutions for customers as well as the managed services who keep these environments running smoothly.  He enjoys a deep dive into the syslog, and can telepathically sense slow and undersized storage.

First customer / project we discussed was a Virtual SAN environment for a construction company. The environment was build on top of Dell R720s and they have 400GB flash capacity in each node and 7x 1.2TB 10K RPM. In this environment MS SQL is running on top of Virtual SAN and Exchange. The SQL database is used for ~ 1000 customers as part of a real time bidding and tracking solution. As you can imagine reliability and predictable performance is key in this environment. Also hosted on Virtual SAN is their ERP system and it is also used for their development environment for their end-customer applications.

What was interesting with this particular project is that there were some strange performance anomalies, as you can imagine Virtual SAN being a new product was a suspect but after troubleshooting the environment they found out that there was a mismatch driver/firmware mismatch for the 10GbE Intel NICs they were using. Further investigation revealed that all types of traffic were impacted. John wrote about it on their corporate blog here, worth reading if you are using the Intel X540 10GbE NICs.

Key take away: Always verify driver / firmware combination and compatibility as it can have an impact.

What pleased John and the customer the most is probably the performance Virtual SAN is providing. Especially when it comes to latency, or should I say the lack of latency as they are hitting sub millisecond numbers. They’ve been so happy running Virtual SAN in their environment that they’ve just purchased new hosts and a DR site with VSAN is being implemented this week. The DR site will be used at first to test VSAN 6.0 and when proven stable and reliable the production environment will be upgraded to 6.0 and the DR site will be configured for DR purposes leveraging vSphere Replication. I asked John how they went about advising the customer to leverage a virtual replication technology which is asynchronous and John mentioned that as part of their advisory/consultancy services they have business analysts on-board which will assess what the cost of down time is and map out the cost of availability and decide a solution based on that outcome. Same applies to de-duplication by the way, what is the price of disk, what is the dedupe ratio, does it make sense in your environment?

While discussing this project John mentioned that he has worked with customers in the past which had two or three IT folks of which one being a dedicated storage admin, primarily because of the complexity of the environment and the storage system. In todays world with solutions like Virtual SAN that isn’t needed any longer and the focus of IT people should be enabling the business.

During our discussion about networking John mentioned that Synchronet has a long history with IP based storage solution (primarily iSCSI), and based on their experience top grade switches were in absolute must when deploying these types of storage. While talking to some of the Virtual SAN engineers John asked about how Virtual SAN would handle switches which have a lower “PPS” (packets per second). The Virtual SAN team mentioned that VSAN was less prone to the common issues faced in iSCSI/NFS environments, John being the techie that he is of course was skeptical and wanted to test this for himself. The results were published in this white paper, fair to say that John and his team were impressed with how Virtual SAN handled itself indeed with relatively cheap switches. For the majority of Virtual SAN deployments their typical customer setup is leveraging 2 VMkernel interfaces each connected to a different switch so that traffic isn’t going outside of the switch, this is what it would look like for those interested:

Host 1 / NIC-A —> Switch-A
Host 2 / NIC-A —> Switch-A
Host 3 / NIC-A —> Switch-A
Host 1 / NIC-B —> Switch-B
Host 2 / NIC-B —> Switch-B
Host 3 / NIC-B —> Switch-B

The second project John mentioned was for a software startup in the healthcare space. They’ve been doing a lot of mergers and acquisitions. Initially they wanted to get 6 VMs up and running but with the ability to scale-up and scale-out when needed. I found the “scale-up” comment interesting so asked what John was referring to. In this scenario the server configuration used was SuperMicro Fat Twin initially deployed with 3 hosts using a single socket and 800GB of flash capacity and two NL-SAS drives. As the company started growing of course the number of virtual machines increased and they have over 70 VMs running currently, simply achieved by adding an additional CPU in each box and add some drives. The question I had was what about flash capacity then compared to disk capacity? John said that they started out with flash overprovisioned simply to allow them to scale-up when required. Especially in the merger and acquisition space where the growth pattern is unknown this is a huge advantage of a solution like Virtual SAN which allows you to both scale-out and scale-up when required. Compared to traditional storage systems this model worked very well as they avoided the huge up front cost (50K USD – 100K USD not uncommon). On top of that, John said that with the majority of storage systems a big discount is given during the initial purchase but when it is time to add a disk shelve that discount has magically disappeared. Also, with traditional storage systems you can fairly easily reach the limits of a storage controller and be stuck with a system which can’t scale to the size you need it to scale. Another problem that disappears when leveraging VSAN.

Key take away: Large upfront costs can be avoided while offering flexibility in terms of scaling and sizing

Synchronet isn’t just an implementation partner by the way, they also do managed services and one of the things they are doing for instance is monitor customer environments leveraging Log Insight. This includes monitoring Virtual SAN, and they’ve created custom dashboard so that they can respond to  issues like for instance when a snapshot removal has failed and solve the problem before an issue arises as a result of it. They can go as far as monitoring the raw syslog feeds if needed, but each time a problem occurs in any environment this is recorded and custom dashboards and warnings are created so that every customer immediately benefits from it. For some customers they even do full management of the vSphere environment.

We had some small talk about VDI. John mentioned that VSAN is great for PoC’s and small test environments because it is easy to get in their, use it and then grow it as soon as the PoC / test has completed. Especially the price per desktop licensing is really handy as it keeps the cost down initially, and at the same time the customer knows what it is paying and getting. From an architectural point of view John mentioned that the majority of their customers use non-persistent desktops and as such the Virtual SAN environment looks different then the traditional server VM environments. Typically less disk capacity and higher flash capacity to ensure performance.

Before we wrapped up there was one thing I was interested in knowing, that was if they tweaked any of the Virtual SAN related settings (within the storage policy or for instance advanced settings). John mentioned that they would tweak the number of stripes per VM from 1 to 3 by default. This is primarily to speed up the backup with Virtual SAN 5.5, preliminary tests are showing though that with Virtual SAN and the new snapshotting mechanism this isn’t needed any longer. While talking about striping John also mentioned that for their hosting services the one thing that stood out to him is that Virtual SAN was performing so well that the customers paying for a lower tier of storage were actually getting a lot more storage performance resources then they paid for and the storage policies were used to ensure that a tier 2 VM wouldn’t receive more resources than a tier 1 VM, pretty neat problem to have I guess.

Key take away: Increasing stripe-width with Virtual SAN 5.5 can have a positive impact on performance. With 6.0 this appears no longer needed.

Last thing John wanted to mention was the VIP Tool (https://vip.vmware.com/). He said it helped them immense figuring out how much data was active and designing / sizing Virtual SAN environments for customers. I think it is fair to say that John (and Synchronet) has had huge success introducing Virtual SAN to their customers and deploying it there where applicable. Thanks John for taking the time, and thanks for being a great VMware and Virtual SAN advocate!