[The Prohacker]

Originally Posted by vissa

Which RAID setup & hard drives do you use, and why (or do you not use RAID at all)?

My large forum server currently uses a SCSI RAID 5 array with 3 10,000 RPM drives. However, I am starting to regret that choice as I understand the performance of RAID 5 writes is not really any better than a stand alone drive. RAID 5 arrays are fast at reads and there is hardware failure protection of course. I now wish I went with RAID 0+1 or a RAID 10 array, which improves both read and write performance and includes fault tolerance. Does anyone know the difference between the two (0+1 vs 10)?

I've decided to add a single large 4th SCSI drive outside the array for daily backups and possibly log files. Of course, I do regular external backups as well. It seems the log file creation (over 2GB every few days) is one of the most intensive write operations that generates a significant constant load -- especially since RAID 5 is not as fast at writes. If I offload those less important files to a secondary drive I'm hoping it will take a lot of the writes off the array. Plus, backups on my server are the single biggest load generator, take several hours, and slow down the forum more than anything else. I believe backing up from the array to another drive could reduce the load and significantly and greatly decrease the time it takes.

-vissa

I inherited our current cluster of servers that are all RAID5. Slowly I am changing the database servers over to RAID10 for the same reasons as you. I am also moving from U160 10k drives over to newer U320 15k ones. I am also looking at Serial attached SCSI instead of moving to U320. IOwait has been a major issue with some of our DB servers and the two servers we have moved from RAID5 to RAID10 have been doing much better. We also changed the IO scheduler in our kernel to deadline.