Software raid help

novadude

[H]ard|Gawd
Joined
Jul 8, 2004
Messages
1,108
Alright, I've got a software RAID 5 set up on a server that is only handling the array.
Server specs: SuperMicro H8DAE, Dual Opteron 275's, 12GB ECC RAM, 3x1TB seagates in RAID 5 on a SM PCI-X card.

The problem is after about 2GB is transferred over at gigabit speeds (~95MB/s due to source limitations) the speed drops sharply to ~50MB/s and then keeps dropping slowly after that.
MTU is set to 9000 on the server, 9014 on the workstation (PCI-e Intel gigabit NIC), switch is an HP procurve 1400-8G


Is there any way to fix the problem, maybe by throwing all of the resources on the server at it? I'm assuming that the array is filling a 2GB buffer of system ram and dropping off in speed, so I'd like to give it full access to the four cores and 12GB of RAM.
 
You've committed the common Internet troubleshooting mistake of not providing enough information.

Which distro and kernel version? Are you using an out-of-tree driver for the drive controller? How are you doing the transfers (ftp, http, cifs, nfs3/4, netcat, aoe, iscsi, something else)? Have you tried a different method? Does this performance problem only occur with network transfers, or with local transfers as well?
 
That would be because I have pretty much narrowed it down to an array problem

Debian, 64bit, 2.6.24-19, standard driver for the controller
problem occurs in local transfers (OS drive to array), ftp, sftp, samba and nfs although ftp/sftp operate at half speed compared to smb and NFS (45MB/s max, drops to ~15MB/s)
 
An Opteron 275 should not have any trouble sustaining 50+ MB/s parity calcs. Are you sure that the array is healthy, and have you checked the SMART data for each drive?
 
An Opteron 275 should not have any trouble sustaining 50+ MB/s parity calcs. Are you sure that the array is healthy, and have you checked the SMART data for each drive?

Yes, the array was healthy and the drives are fine. I nuked the array and set up single drives and now get >100MB/s sustained transfers on each drive
 
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