Raid 5 Array With Mismatched Disk Speeds

[DirtySouth]

We currently have a server operating with a directly-attached storage array. This array has 13 drives configured in a single Raid 5. The drives are varying manufacturers and varying speeds. I'm not concerned about the manufacturers...I realize this isn't the ideal situation.

My question is, if we were to group the matching drives, based on speed, into logical disks, would we get better read/write performance? In other words if we to group all of the 10K disks into one logical raid drive and then all of the 15K disks into a separate logical drive, would it perform better than it is currently. Right now, we are receiving reports of very poor read/write times.

Thanks in advance.

 

[Gatorbait]

Are you using a HW Raid controller or is it software raid driven?

 

[GhislainG]

Yes, but the difference shouldn't be outstanding. The gain should be from the 15K drives RAID that should provide faster access, but total throughput should decrease slightly with less disks.

How is the directly-attached storage array connected to your server? That can have a significant performance impact.

 

[Gatorbait]

Is this a SAS, SATA, SATA 3G, or SCSI array? Is the OS on this drive too, or is it on a separate drive?