In our last issue, we discussed how to build your own NAS box using FreeNAS.
This time we have evaluated it for performance, and to see where it really
stands, we've even compared it against Microsoft Server Appliance Server kit.
You can download the Microsoft Server Appliance kit from Microsoft's web site.
To use it, you will also need Windows 2000 Server installed on your NAS box. The
appliance kit installs on top of that. The kit comes with clear cut instructions
on how to create a NAS appliance. You can download the kit from Microsoft's
website. Just go to the downloads section, and search for server appliance kit.
You can download FreeNAS from www.freenas.org. Both, an ISO and the source code
can be downloaded. Even a VMware version of the same is also available for
download.
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As both software allow you to create your own NAS box, and are freely
downloadable from the Internet, it was really worthwhile doing it. For this,
both were installed on the same hardware that we used for building our 1.3 TB
NAS box last month, i.e. a PC with an AMD 64 Athlon X2 4800+ processor, 512 MB
RAM, four 500-GB SATA hard disks, and 1 Gbe Ethernet card.
How we tested
To stress the NAS box, we used 19 nodes to generate the load. Each node was
connected to the NAS box over a Gbe link. We used the industry standard NetBench
7.0.3 benchmark to stress the NAS box's I/O capabilities. The test was
designed such that initially, the loading started from one client and
progressively the remaining 18 nodes joined in. The objective was to measure the
peak output that the NAS box could provide, beyond which I/O would drop. This
gave us the average throughput and response time of the NAS box. Ideally, as the
throughput increases, the response time reduces and vice versa. During the
setup, the first hurdle we faced was that while FreeNAS supports software RAID,
Microsoft's Server Appliance kit does not. Both do work on hardware RAID
though. So we first tested each without RAID, and then with hardware SATA RAID 1
and RAID 0.
The max throughput given by FreeNAS is quite good, but it drops sharply with an increase in the number of clients. Likewise the response time also goes up |
Which is better?
After running the load tests for three consecutive days, we discovered that
FreeNAS scored higher in all average throughput tests, both with and without
RAID. It gave a maximum throughput of 263 Mbps without RAID, but as we increased
the load, there was a steep decline in the throughput and the minimum we got was
188 Mbps. Likewise, its minimum and maximum response time were 0.143 ms and
1.620 ms respectively. With RAID 1, it showed a maximum throughput of 207 Mbps
and minimum throughput of 142 Mbps. Likewise the maximum response time it gave
with 19 clients was 1.440 ms and minimum was 0.193 with a single client.
Surprisingly, with RAID 0 its performance was more or less similar as without
RAID. This was strange considering that RAID 0 is supposed to enhance
performance.
The NAS box with Microsoft Server Appliance kit without RAID gave a maximum
throughput of 152 Mbps, and its throughput didn't drop too much with an
increase in the number of clients. It hovered around 150 Mbps. Its response time
on the other hand, did see a steep rise however. It started with a minimum
response time of .2 ms, which rose to a whopping 2.048 ms with 19 clients. With
RAID 1, the maximum average throughput of Windows Server appliance dropped to
122 Mbps and the maximum response time with 19 clients clocked 1.944 ms. RAID 0
somehow showed similar performance results as without any RAID.
The overall throughput of Windows Server Appliance is lower than FreeNAS, but it remains stable with an increase in the number of clients. Response time, however, increases. |
Bottomline
So overall, the good thing about FreeNAS was that it showed a higher throughput
than Windows Server Appliance. Even though, it saw a steep decline in throughput
with an increase in load, its minimum throughput still remained above the
maximum throughput of Windows Appliance Server. The positive thing about Windows
Server Appliance was the stable throughput it gave irrespective of the number of
clients. No matter how many clients we used to put the load onto it, the
throughput remained fairly stable, which is a good thing. Interestingly, its
response time went up.