Hardware vs Software RAID

[JeffBlair]

Hey all. Well, I found a good deal on a older 3ware 9500s-8 card. I've got it setup as a 5x2T RAID5 right now. And, I might be adding another 2T to it in the near future.

So, what I was wondering is, this. I know that card's old. So, would it be better to just say forget it, and backup what I have on there now, and convert it over to a software RAID5? I mainly use it for streaming my DVD/Blue-Ray collection/Movies/Backup of PC's. Sooner is better then later so I don't have to re-do a lot of stuff.

And, I have LVM on top of the RAID5 if that makes any diffidence.

Thanks all.

Here's what I got really quick from my tests on the 3ware card in Linux:

hdparm -tT /dev/media/media

/dev/media/media:
Timing cached reads: 3296 MB in 2.00 seconds = 1648.82 MB/sec
Timing buffered disk reads: 210 MB in 3.02 seconds = 69.51 MB/sec
============
grep MemTotal /proc/meminfo
MemTotal: 2035188 kB
============
grep bogo /proc/cpuinfo
bogomips : 5866.76
bogomips : 5866.46

 

[john4200]

For a media volume, I like SnapRAID:

http://snapraid.sourceforge.net/

 

[drescherjm]

hdparm -tT /dev/media/media

/dev/media/media:
Timing cached reads: 3296 MB in 2.00 seconds = 1648.82 MB/sec
Timing buffered disk reads: 210 MB in 3.02 seconds = 69.51 MB/sec

This looks very slow although hdparm is not that accurate since the test is over in 3 seconds..

How about dd instead on a file that is at least 2 times your memory size. Most current distributions dd should give the rate after it finishes.

Here is an example from one of my linux software raid 6 arrays here at work with 9x hitachi 2TB 7K2000 on a core2quad Q9550 at stock 2.83 GHz

datastore3 ~ # free -m
             total       used       free     shared    buffers     cached
Mem:          3958       3909         49          0       2439       1135
-/+ buffers/cache:        333       3624
Swap:         3624         52       3571

datastore3 ~ # dd if=/dev/vg1/imagedata of=/dev/null bs=1M count=16000
16000+0 records in
16000+0 records out
16777216000 bytes (17 GB) copied, 20.6166 s, 814 MB/s

 

[Red Falcon]

Unless you have that card on a PCI 32-bit 66MHz, 64-bit 33MHz, or 64-bit 66MHz slot, it will be bottlenecked horribly. Either way, software or hardware RAID, you will get lowered performance.

However, if you are using it on a faster slot, then you should be good.