[Phoenix32]

Now with all of that said, keep in mind that differences of 0.1 or 0.2 MB/sec are not worth comparing. You can get variance by that much on the same equipment on different test runs.

The theoretical limit for 100baseT is 12.5MB/sec if I remember correctly, and as you can see, with FTP we are approaching that with Reads. Writes on the other hand are a different story. In almost every test I have ever run, you cannot get more than about 1/3 to 1/2 of the 100baseT bandwidth for Writes.

I have used 5400 RPM Quantum 30 GB drives, 7200 RPM Quantum 30 GB drives, 7200 RPM Seagate 250 GB drives, 7200 RPM WD drives, and a host of others. With 5400 RPM drives, you will loose some speed from what I posted here due to access times of these drives. 7200 RPM drives, old or new, will get you near the limits. If you use newer and faster 7200 RPM drives, you can get an increase of around 0.75MB/sec transfers under ideal conditions, due to access times of the drives, but as a general rule, 7200 PRM drives of any type, old or new, pretty much reach the limits you are going to get on a day in and day out usage. I am not aware of any 10000 RPM EIDE drives available, so forget that idea. Plus they would be very expensive for very little gain, if any. If you want maximum speed, then like most other things in the computer world where RAID is involved, look to the drive access times, but do not expect huge amounts of gain.

The 4100 has 4 IDE and the 4000 only has 2. It would seem reasonable that the 4100 would be slightly faster (and has been reported incorrectly as so on this forum many times). But the fact is, I have 3 SNAP 4100 units and 6 SNAP 4000 units to test with and in all cases, the 4000 and 4100 have been on par with each other (and I have done hundreds of hours of testing). If we were using Gigabit LAN, or a faster processor, or 10000 RPM drives, it might make a difference, but we aren't. With the CPU as it is, 100baseT, and 7200 RPM drives, the difference is just not there. THEY ARE THE SAME IN PERFORMANCE! Okay got it? Good!

And what about memory? It seemed reasonable, even to me, that more memory would be good and would be faster. Well guess what? Doesn't happen. I have tested with 32MB, 64MB, 128MB, and 256MB. So long as you are using the smaller drives and not using JVM, there has been very little performance gain above 64MB. 32MB is slower, but 64MB is enough. Now I am not saying there is no gain or not to do it. I am just saying not to expect a lot in performance gain with more than 64MB. Of course this is with default settings. If you want to go in and mess with RAID stripe sizes, who knows.

Now for the caveat to the memory thing. -IF- you are using larger drives (say 120 GB or larger), 64MB does take a small perfromance hit. In this case, 128MB seems to be better. Rather than start a long drawn out discussion as to why this is, I will just leave it to your own ideas. But, if you are using 120 GB drives or larger, you can get a small performance gain with 128MB of memory.

Now a caveat to the caveat. JVM installed and running changes the whole picture. When running JVM, it is suggested to use 128MB or more memory. I will go farther and say it is required, not just suggested. As an example of this, I was testing a 4000 with 64MB and JVM installed and running. Anything more than about 100MB worth of data to be transfered would get aborted. In other words, if you are using JVM, you do in fact need 128MB of memory or you will get random errors and crashes, in my opinion. I have tested a 4000 with 4 x 250 GB Seagate 7200 RPM drives with 128MB memory and JVM installed and running. I did not have any problems and did get full speeds as reported above. However, if you are going to use JVM and have large drives, I would suggest 256MB. Better safe than sorry. But do not feel you have to, 128MB did seem to be fine in each test, and I did not run into any problems with it myself. Your mileage may vary.

To wrap this up, here is the general rule(s) of thumb for SNAP 4000/4100 speeds. Assuming you are using the proper amount of memory for your configuration, and good fast access 7200 RPM drives, you should expect at or near the following speeds in FTP (SMB will be slower). The 2x00 units should be near these numbers and of course the 1x00 units will be slower due to a slower CPU (I have a 1000 also, but did not feel it was worth pursuing).

JBOD, RAID 0, and RAID 1: 6 to 6.75MB/sec Write and 10.5 to 12MB/sec Read

RAID 5: 4.0 to 4.5MB/sec Write and 10.5 to 11MB/sec Read


I sincerely hope we can now lay this question to rest. If you do not agree, hey more power to you and I got no problem with that. But, if you want to dispute these results, you better be prepared to back it up with proof and repeated controlled testing.