[Phoenix32]

Okay, I don't mean to be all pissy about this subject (although people have come to expect it from me), but it seems like every month or so this subject comes up. People ask, we answer the questions, then a month later someone else asks the same thing again. It gets kind of old after a while. I hope this will answer the questions on speed once and for all. I did these tests last month for David (blue68f100) in e-mail for positive answers. This is a copy of some of that e-mail.

This applies to the SNAP 4000 and 4100. Speeds for the 2000 and 2200 will be similar and speeds for the 1000 and 1100 will be slightly less due to a slower processor. Obviously, the 1x00 and 2x00 units do not support RAID 5.


Test conditions:

My PC is a Pentium 4 Northwood 3Ghz hyperthread with 2 GB of Dual Channel 2-2-2-5 DDR with PAT on (the system is plenty snappy). I am using WinXP Pro SP2. I have a pair of WD SATA 120's in RAID 0. I am using the Intel i875 Chipset with the CSA Gigabit LAN. In case you do not know what CSA Gigabit is, it is an Intel Gigabit LAN that is connected directly to the northbridge so that it comes off the northbridge instead of the southbridge. This gives better Gigabit performance than can be had from Gigabit LAN over the southbridge PCI bus.

My PC is connected to a Gigabit Router with 4 "switched" Gigabit ports (it is not a hub like most routers are). The test SNAP 4000 is connected to an 8 port Gigabit Switch of the same brand and series as the Router. The Router and Switch are connected directly. I am not using jumbo frames, as the SNAP would not appreciate that and it would slow it down rather than speed it up. I get pretty respectable Gigabit speeds over this exact setup. All other network activity was suspended for the duration of the tests.

The SNAP is a SNAP 4000. OS v 3.4.805 with 64MB SDRAM and 4 x 30 GB Quantum Fireball LM 7200 rpm drives with 13msec access times as measured by Spinrite. The drives were freshly low level formatted with the Quantum utility, Spinrite scanned, and then freshly formatted in the SNAP 4000. The SNAP was set to factory defaults with the exception of the server name and workgroup.

I did Write and Read transfer speed checks in RAID 0 with a 2 Drive array, RAID 0 with a 4 Drive array, RAID 1, and RAID 5 with a 4 Drive array. In both cases of the RAID 0 with 2 Drive array and the RAID 1 with 2 Drives, I used Drives 1 and 3 for the array so that the drives would not be on the same IDE channel. Speeds were measured using AnalogX Netstat Live. Results are as follows. All tests were conducted to and from the exact same locations on the PC and SNAP with test files deleted between tests. The test file was a single image file of 626,258,076 bytes (597MB).

NOTE 1: The 4100 will not get faster speed with 4 IDE channels (one for each drive) rather than the 2 IDE channels used by the SNAP 4000. My experience with both 4000 and 4100 units using the same drives has indicted this speed difference is negligible. More on this later.

NOTE 2: Using faster modern drives (access times) may also speed things up slightly, but as you will see from the RAID 0 results compared to the others, I remain skeptical it would be much if anything.

NOTE 3: While I did not include the results here, I have done some testing with 64MB, 128MB, and 256MB SDRAM installed. With the 4 x 30 GB arrays, it made NO DIFFERENCE AT ALL! NONE! ZERO! ZILCH! With larger drives, this will change the picture, or if using JVM. But I have yet to see any real difference when using 4 x 30 GB drives and JVM not installed.

NOTE 4: I have also used OS v 3.4.807 and OS v 4.0.860 on both SNAP 4100 and SNAP 4000 units in similar configurations and seen no difference in speeds.

NOTE 5: I cannot explain why the RAID 1 Mirror yielded a higher Read speed than either of the Striped RAID arrays (RAID 0 and RAID 5). This should not be, but it was.


RAID 0, 2 drives, 1 and 3: Write = 4.9MB/sec, Read = 5.9MB/sec

RAID 0, 4 drives: Write = 4.9MB/sec, Read = 5.9MB/sec (the average was the same as RAID 0, 2 drives in Real Time)

RAID 1: Write = 4.5MB/sec, Read = 6.3MB/sec (I have no idea why the Read speed is higher here than in RAID 0 which should be higher)

RAID 5, 4 drives: Write = 3.5MB/sec, Read = 5.9MB/sec

Speeds were consistent and as would be predicted with the exception of the one anomaly of the RAID 1 Read speed.

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