Hardware vs. Software SCSI raid..


Dave Satchell

I have a customer with a Adaptec 39160 SCSI card that wants to set up Raid-
1 (mirroring).

I was going to just use software raid but I just read that you can't load
the OS onto a array with software raid (makes sense actually and I think I
remember this as being the case now).

So my question is, with the existing SCSI drive (68pin), the existing
Adaptec 39160, and a couple of spare 80pin SCSI drives (with 68pin
adaptors) that I have laying around; what is would be my best/cheapest
solution for setting them up with a Raid-1 array that contains the OS and
data drives?

Thanx, Dave.



Steve Duff [MVP]

The 39160 is not a hardware raid1-capable controller. At a minimum you need the 29320R/39320R to handle mirroring in the controller

Software mirroring is not an appropriate solution for a production environment, for a number of reasons: It degrades performance
somewhat, management and alerting is limited, and recovery can be difficult depending on the failure scenario. It also requires
dynamic disk format which is not recognized by partition management utilities. At any rate the added cost for a hardware raid1
controller is insignificant to the overall cost of a SCSI-based server.

If you are going to switch controllers, the LSI Logic 2x320R series are quite good and would be my recommendation. Unless you want
multi-channel mirroring (which is pointless with only two drives), there is no compelling reason to move up to a full RAID5
controller such as the Adaptec 2000-series or LSI 320s in your application.

Steve Duff, MCSE, MVP
Ergodic Systems, Inc.




Hi Dave,

There are important benefits using a SEPARATE HARDWARE Raid controller
compared to a software solution.

1. Drive imaging tools backup and restore arrays at bios level (without any
Dynamic disks may not be recognized / supported.

2. If a contained OS cannot boot, move the array (controller + attached
to another PC (install drivers first) and start repairing from there.
This saved me once (IDE raid btw).


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