vSphere 5 - Virtual Storage Appliance

In one of the comments to numerous blog articles I have been reading lately I noticed quite a sceptic opinion about vSphere 5 Virtual Storage Appliance (VSA) with regard to its capabilities and price. That was quite motivating to spend a day on reading about VSA and making my own opinion about it..

So, here is a short overview of VSA from vSphere admin.

The main goal of VSA is to provide SMB companies with shared storage without buying physical NAS or SAN itself. Instead VSA will use internal storage of your ESXi hosts to create shared NFS storage that will be presented as a single entity to all hosts in your vSphere. This is how it looks with 3 node configuration.

With two node scenario vCenter play role of third node to ensure there is still majority of nodes in the cluster once the second node fails. This helps to avoid any kind of split-brain scenario.

VSA brings you all benefits you can get with shared storage: HA and DRS cluster, vMotion, Fault Tolerance - yes, FT now is supported on NFS.

The data redundancy will be provided by RAID-10 on local storage and RAID-1 across your hosts. Even though you can enable VSA only on 3 ESXi hosts the shared NFS storage can be presented to other hosts in your datacenter. With current release of VSA you can run  only 1 VSA storage cluster per Virtual Center.

Before the installation of VSA is started you need to review your storage capacity. You have to keep in mind that with all RAID protection of VSA you will get only 1/4 of raw disk space in your shared storage. I think it would be a nice option if VMware could provide a choice on RAID options in next release of VSA, at least at local storage level. If performance of your datastore is not so important I personally would prefer to use RAID-5 on internal storage and RAID-1 across nodes. According to the latest information VSA will not care what the local RAID is, but VMware will support VSA only when it works on RAID-10.
Once you setup VSA you cannot add more disks to storage cluster.

First you need to install VSA manager that will integrate its plugin into your vSphere client. After that you run cluster configuration wizard which will help you to choose compatible ESXi hosts, deploy 1 VSA appliance per each of these hosts and offer additional options as configuration of vMotion, HA and DRS.
On each node of storage cluster VSA will create two volumes: one will host local NFS storage, another one will host NFS storage replica of of neighbour node. Locally deployed VSAs are responsible for presenting local NFS datastore, for synchrous mirroring of NFS datastores and for failover actions when one of the node fails. After installation is completed you get 3 NFS storages that are fully redundant and there is no single point of failure.

Basically, you are protected on 3 levels:

1. Local disk failure won't impact any functionality and will be fully transparent for ESXi host and VMs running on it
2. Host failure won't impact shared storage. This event will trigger VSA to bring online replica of NFS storage of the failed node. It will be presented by VSA appliance with the same ip address. Again, it will be fully transparent for ESXi hosts and VMs running on failed NFS datastore. VMs that were running on failed node will be restarted on remaining nodes by HA
3.You can go further and enable FT for your VMs whose availability is critical to your environment.

VMware claims you get 99,9% availability with VSA and HA properly implemented.

I was trying to calculate the price of such solution for some average small office. You might have absolutely different prices, requirements for your hardware' specs, etc. So I would recommend you to figure your small or branch office ideal architecture, get your local prices, consider possible discounts and make own calculation.

So, my ideal small/branch office would have 3 HP Proliant DL380 G7 servers with 6x600GB 10K disks per each server. These would give us 10.8 TB of raw disk space. Considering local RAID-10 it gives us 5.4TB. After we implement RAID-1 across nodes we will end up with 2.7 TB, which will be presented in 3 NFS datastores of 900 GB each. I think it is quite a big overhead, that's way I thought maybe there is a possibility to use RAID-5 to reduce such overhead, but on the other hand you have fully redundant shared storage.

First google result (http://www.varshop.it/store/comersus_viewItem.asp?idProduct=118025) was 368 euro per disk. All disks will cost me 18x368= 6624 euro.
Announced price of VSA is $5,995. I guess for Europe it will be the same number, but only in EURO. So, the final price of fully redundant storage is 6624 + 5995 = 12619 euro. As a good indicator of price I would like to use eur/gb ratio. In our case the price for 1 gigabyte will be 4.67 euro, which is actually quite a good result.

I guess there could be cheaper products of shared storages on the market, or even freeware like Openfiler or FreeNAS. However, you have to consider following serious benefits of using VSA:

1. Very easy installation. All is done in familiar vSphere interface and wizard will take care of the proper configuration and order of steps. I can compare VSA to only competing product I have used so far - Openfiler. You need sometime to get use to new naming of Openfiler. Its GUI was not very obvious for me.

2. Integration in vCenter - all monitoring and management done in one place. I guess there will be preconfigured alarms for VSA.

3. One vendor support - I already have had several cases where HP hardware or VMware software could be a root cause of our issues. The bad thing about it is that you have to prove to support service that it is their product causing problems. I am sure you have also had the similiar situations. With your VMs running on VSA you always have one responsible support service. When we had issues with iSCSI storage on Openfiler I couldn't even figure out what to do since I have zero troubleshooting experience with Openfiler and have close to zero knowledge of Linux.

4. Node fault tolerance - if you use some Windows server or Openfiler you also need to take care about scenario where one of your shared storage node fails. With VSA it is builtin functionality.

5. You get all benefits of NFS datastore, like automatic thin provisioning, easier backup,

6. VMware is going to present limited time offer VMware vSphere 5 Essentials Plus and the VMware vSphere Storage Appliance for $7,995, which represents a 40 percent discount on the list price of the VMware vSphere Storage Appliance. Nice, huh?
The only disadvantages of VSA I can think of now is quite a big overhead, but again, you need to consider price per GB as a trustable metric for your storage.

I wish I could compare it with HP Virtual Appliance with regard to functionality and pricing, but I really don't have so much free time. Feel free to comment here with competing products's names and their benefits over VSA.

I would also appreciate any comments about quality of my posts (including my English :) ) and any wrong conclustion or mistakes I could make here.

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