Multi-Client iSCSI Evaluation

As virtualization becomes more and more popular even in home / power user settings, the importance of the iSCSI feature set of any COTS NAS can't be overstated. Starting with our ioSafe 1513+ review, we have started devoting a separate section (in the reviews of NAS units targeting SMBs and SMEs) to the evaluation of iSCSI performance. The Asustor ADM only allows for iSCSI LUNs to be created as regular files and doesn't allow for multiple sessions to a single target. Even the Seagate NAS Pro units have this capability. Fortunately, from a review perspective, we only had one iSCSI configuration to evaluate.

We evaluated the performance of the Asustor AS7008T with file-based LUNs only. The standard IOMeter benchmarks that we used for multi-client CIFS evaluation were utilized for iSCSI evaluation also. The main difference to note is that the CIFS evaluation was performed on a mounted network share, while the iSCSI evaluation was done on a 'clean physical disk' (from the viewpoint of the virtual machine).

Performance Numbers

The four IOMeter traces were run on the physical disk manifested by mapping the iSCSI target on each VM. The benchmarking started with one VM accessing the NAS. The number of VMs simultaneously playing out the trace was incremented one by one till we had all 25 VMs in the fray. Detailed listings of the IOMeter benchmark numbers (including IOPS and maximum response times) for each configuration are linked below:

Asustor AS7008T - LUNs (Regular Files) - Multi-Client Performance - 100% Sequential Reads

 

Asustor AS7008T - LUNs (Regular Files) - Multi-Client Performance - Max Throughput - 50% Reads

 

Asustor AS7008T - LUNs (Regular Files) - Multi-Client Performance - Random 8K - 70% Reads

 

Asustor AS7008T - LUNs (Regular Files) - Multi-Client Performance - Real Life - 65% Reads

Synology provides multiple ways to create iSCSI LUNs, each with different pros and cons (we are only looking at the bandwidth and response time numbers in the graphs above). The problem for the AS7008T lies in the fact that there are only two network links. This severely hampers the benchmark numbers and causes performance to degrade beyond a couple of clients for the real life 60% random / 65% reads workload. The other traces have the same behaviour as the multi-client CIFS workloads, but Synology just provides more alternatives to the end-user.

Multi-Client Performance - CIFS on Windows Encryption Support Evaluation
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  • Lycoming360 - Sunday, November 30, 2014 - link

    I'd love to have that rebuild speed in my Synology unit. But, you certainly do pay for that speed!
  • Jcowley - Sunday, November 30, 2014 - link

    Maybe I don't understand but what are you getting for your $1500 over building your own NAS with equivalent/better hardware?

    I understand the whole off-the-shelf and it just works aspect is worth a bit but $1500 seems extortionately high for what is essential just hot-swap bays on top of anything you could build yourself.
  • bill.rookard - Sunday, November 30, 2014 - link

    I agree, I have my NAS, rackmount case (no hot swap sadly), and 5 2tb drives for a total of about $1000.00. (Drives were purchased at a slight premium to what they can be had for now).
  • DigitalFreak - Monday, December 1, 2014 - link

    Here we go again. Not everyone wants to spend the time to research, build and install their own NAS. Having a single point of contact for support and software updates is also worth the $$ to some people and especially businesses.

    That being said, I do think the Asus is overpriced compared to a Synology, even taking into consideration the Haswell hardware.
  • bill.rookard - Monday, December 1, 2014 - link

    I don't disagree at all with that, there certainly is (as evidenced by the expanding options by various companies) a market for a one-stop, plug in the drives, connect the ethernet cable and power it up units. People are even willing to pay a premium for such a device in a space efficient package.

    However, any decent tech guy should be able to put together a decent simple Linux-based box (which is what FreeNAS is based off of) for file servicing. These days, with the hardware which is available, the bar to putting together something small, or large, power efficient, and rock solid is much lower and much less expensive than many people realize.
  • PrimozR - Monday, December 1, 2014 - link

    FreeNAS is based off FreeBSD. Still Unix, not Linux though.
  • bill.rookard - Monday, December 1, 2014 - link

    Yes, I know it's based off of FreeBSD... technicalities... :) I guess I should have, since I was just using a basic generalization of the type of OS, that it was 'based of *nix' since they share very similar underpinnings.
  • Black Obsidian - Monday, December 1, 2014 - link

    I don't think anyone is disputing that SOME premium is justified by the value of a pre-built, supported machine. The question seems to revolve around how MUCH premium is justified, especially in larger NAS boxes like this one.

    Having recently built a media server with virtually identical specs, I can say that with Asustor you're paying a 200% markup for the convenience of pre-built and support. Which seems a bit steep, especially from Asustor, which doesn't have the brand cachet of Synology.
  • peterfares - Monday, December 1, 2014 - link

    Here we go again. People thinking these insane markups are justifiable.
  • peterfares - Monday, December 1, 2014 - link

    I'm sure it makes sense in SOME cases to buy these prebuilts but some people seem to really over-value their time.

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