>> If you replicate pairs of servers, how come you're still using RAID 6? > > This is actually a very good question. So I guess their are 3 ways of doing this. > > 1) use JBOD and put a filesystem on each of the 16 drives and mount them on 16 points. However since gluster does not support RAID, to get redundancy I would need to unify 8 of the drives and distribute across the two sets. This would in my opinion waste a lot of disks. > > 2) use software RAID... the first issue is that hardware is now faster (at least with 3ware 9650SE cards). The second is that since my motherboard does not support 16 drives I would need a controller anyway, so why not use the free RAID? > > 3) Hardware RAID, the option I selected. The next question was RAID 5 or 6. With 16 drives I found that it makes a lot of sense to use RAID 6 since it is very easy to run into another error before I fix a disk. > This is a reason I'm interested in Solaris. In many situations, the software raid on Solaris (RAID-Z) is faster/cheaper/more reliable than hardware RAID because it understands the filesystem. >> I saw the note in the technical faq about --disable-direct-io-mode. ?What >> does this do, and why is it needed to perform Xen migration? > > Not sure, would need to ask someone else, all I know is it takes me from over 100 MB/s to 22 MB/s. : ( I'll search the list or post a message about this one. Thanks again.
