NAS Units as VM Hosts: QNAP's Virtualization Station Explored
by Ganesh T S on August 18, 2014 10:15 AM EST- Posted in
- NAS
- Storage
- Virtualization
- QNAP
SMB 3.0 Evaluation and VM Performance Impact
QNAP's QTS 4.x is the only COTS NAS operating system that we are aware of with SMB 3.0 support. As a bit of a background, SMB 3.0 was introduced with Windows 8 and Windows Server 2012 as an update to the file-sharing protocol used in Windows systems. It brought in a number of changes including SMB Direct Protocol and SMB Multichannel. Security enhancements such as end-to-end encryption and a new AES-based signing algorithm also make it attractive for usage in business enviromnents.
QTS allows for setting of the maximum allowed SMB version. While SMB 3.0 shares turned out to be accessible even in Windows 7, enabling the SMB Encryption feature for a Samba share while setting up the shared folder rendered it inaccessible (except under Windows 8 and Windows Server 2012). For our evaluation, we created a Windows 8.1 VM in our NAS testbed and repeated our usual NASPT / robocopy benchmarks on a plain SMB 3.0 share and one on which SMB encryption was enabled. In addition, we also repeated the test with the Windows 8.1 VM on the TS-451 active and being loaded with our heavy Internet browsing workload. The graph below presents our observations.
At the very outset, it is clear that enabling SMB encryption causes a huge hit in performance. It appears that the limitation is on the encryption rate, which seems to be topping out at 20 MBps. In the more interesting case of VM vs. non-VM, we find that, with the VM active, there is definitely a loss in performance. However, we doubt that it is much of an issue for even power users in home scenarios. Obviously, the penalty is much bigger for multi-client scenarios since the network ports can't be link-aggregated any more. That said, most home users don't even have routers supporting 802.3ad link aggregation. For such consumers, with the help of Virtualization Station, the second network port of the QNAP TS-451 can actually be put to better use (as a dedicated link for a VM / 'computer') than just a failover link for the NAS.
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Marthisdil - Monday, August 18, 2014 - link
Except be cheap - when you could build a "server" out of a desktop PC that can do a lot of the same stuff, for less money.deeceefar2 - Monday, August 18, 2014 - link
I could, and have done that in the past. But for MUCH more time invested and with many more support head aches. I use at least 1/2 of all of the features of this box, and I challenge you to build a system that does that for significantly less money using similar power draw without spending months configuring and maintaining it.isa - Monday, August 18, 2014 - link
A thoughtful article overall, so thank you Ganesh. I especially focused on the "power user application scenarios". I get #3 and #1, but #2 baffles me. Why must I run ubiquity's apps in a VM? Since that app comes in apple/win/linux flavors, can't one just download the appropriate version for one's NAS and run it without a VM? Why is a VM required to run Ubiquity or any other home automation app if it's offered in a version compatible with my NAS's OS?ganeshts - Monday, August 18, 2014 - link
Does the NAS vendor provide support for unofficial packages? Most vendors I have talked to wash their hands off all warranties / support once you start messing around in SSH. To be frank, for the average user, it is quite easy to mess up the NAS installation (particularly when the extraneous package they want to install comes with a big train of dependencies).isa - Monday, August 18, 2014 - link
Good points, and I agree.Oyster - Monday, August 18, 2014 - link
Ganesh, awesome work. Thanks for listening to the feedback and covering these details. Very well done article.For your next, can you please cover a showdown between Synology and QNAP OSes (including features like apps, VPN, etc.)?
Arnok666 - Saturday, October 17, 2015 - link
+1shodanshok - Monday, August 18, 2014 - link
Hi Ganesh, thank you for the good review.However, I strongly disagree on the chosen Raid level: if you want to run a virtual machine at full speed, you should really use Raid10 rather then Raid5. The problem with Raid5 is that typical 4KB random writes will trigger full stripe read/modify/write, which will lead noticeable slower VM performance.
I personally faced off this very problem some time ago, with a custom Linux mdraid build running some (5+) VMs: switching to Raid10 drastically boosted performance.
Regards.
ganeshts - Monday, August 18, 2014 - link
Thanks for the note. Most consumers buying the TS-451 are looking for optimal balance of performance and capacity. With 4x 4 TB drives, RAID-5 gives 12 TB of effective storage, while RAID-10 gives 8 TB. I agree that in performance sensitive use-cases, the appropriate RAID level must be chosen.Another reason for choosing RAID-5 is that it typically has the worst performance (along with RAID-6) making it a good test of stressing the I/O and other platform capabilities of different NAS models. All our NAS reviews use RAID-5 for comparative benchmarking even though it might not be a suitable RAID level for a particular application.
tuxRoller - Monday, August 18, 2014 - link
So, xen but not kvm? You're doing your reader a disservice by ignoring the third most popular virt platform.