You didn't give much detail about the hardware, but you mentioned a PE2950 which I assume is Dell Power Edge 2950. I worked with some of these last year and our standard storage configuration was 4 internal disks configured as a single RAID 5 volume using the embedded RAID controller. Actually what I had recommended was 6 smaller internal disks for the same price.<br>
<br>The RAID 5 provided an acceptable balance between capacity, protection, and performance. We did some minimal testing to see if reconfiguring the same hardware with mirroring (was it 2 RAID 1 volumes or 1 RAID 1+0 volume?) would provide a performance boost (at the expense of capacity), but we did not notice an meaningful difference in our application. Your mileage may vary.<br>
<br>Rick<br><br><div class="gmail_quote">On Thu, Mar 6, 2008 at 6:58 PM, Scott R. Ehrlich <<a href="mailto:scott@mit.edu">scott@mit.edu</a>> wrote:<br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
So I've learned a valuable RAID 0 lesson, and it fortunately was not a major<br>
catastrophy. I got lucky, and had a workable-enough backup on tape to make the<br>
user who needed some data happy.<br>
<br>
Now, from the OS side, LVM is an option. Say the RAID controller only allows<br>
hardware striping or mirroring for logical volumes, but I want to use more than<br>
two disks, and I don't want the RAID 0 problem again.<br>
<br>
When I get a replacement disk and build the system from the ground up again, I<br>
could, conceivably, use hardware RAID 1 for the OS on two disks, and CentOS 5<br>
64-bit's LVM for software RAID 5 (or maybe 1+0 if available) on the remaining<br>
for 4 disks, maybe 3 disks as active and the 4th as a hot spare?<br>
<br>
I've never had much faith in software raid, since it is not hardware-based, and<br>
there would be a performance hit, but in this case, it could be an option.<br>
<br>
Insights from the OS-created RAID experience welcome.<br>
<br>
Thanks again.<br>
<br>
Scott<br>
<br>
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