On Thu, Nov 14, 2013 at 12:23 PM, James B. Byrne <byrnejb at harte-lyne.ca>wrote: > Arch = x86_64 > CentOS-6.4 > > We have a cold server with 32Gb RAM and 8 x 3TB SATA drives mounted in > hotswap > cells. The intended purpose of this system is as an ERP application and > DBMS > host. The ERP application will likely eventually have web access but at > the > moment only dedicated client applications can connect to it. > > I am researching how to best set this system up for use as a production > host > employing RAID. I have read the (minimal) documentation respecting RAID on > the RedHat site and have found and read a few online guides. Naturally, > in my > ignorance I have a bunch of questions to ask and I probably have a bunch > more > that I should but do not know enough yet to ask. > Are you going to use hardware or software raid? > > >From what I have read it appears that the system disk must use RAID 1 if > it > uses RAID at all. Is this the case? If so, is there any benefit to be > had by > taking two of the 8 drives (6Tb) solely to hold the OS and boot partition? > Should these two drives be pulled and replaced with two smaller ones or > should > we bother with RAID for the boot disk at all? > > Given that one or two drive bays will be given over to the OS what should > be > the configuration of the remaining six? It appears from what I have read > that > RAID 5 is the only viable option. It also appears that the amount of > storage > What about RAID10? I've read that running a database server on raid5 isn't recommended, but raid1 or raid10 is recommended. > available on a RAID5 array with N members is N-1/N. I also read that as the > number of members increase both latency and the risk of data loss > increases. > As the amount of disk space we have in this unit (24Tb) is greater than the > total storage of all our existing hosts it appears that a RAID5 array of 5 > units would leave at least one hot spare in the chassis and two if the OS > is > put on one disk. > Space efficiency is less than that of raid5. Rather than 1-1/n with raid5 you have 2/n with raid10. > > Alternatively, the thought comes to mind that we could do a RAID1 with two > RAID5 arrays each of which have 3 drives. Whether one would actually want > to > do that seems to me a bit questionable but it seems to be at least > possible. > You're suggesting a raid5+1 or raid51 http://en.wikipedia.org/wiki/Nested_RAID_levels I wouldn't suggest nesting software raid if you can avoid it for the complexity. There are reasons to create a raid array with two hardware arrays, but I'd avoid doing so. > > Comments, suggestions, caveats? > > Regards, > > -- > *** E-Mail is NOT a SECURE channel *** > James B. Byrne mailto:ByrneJB at Harte-Lyne.ca > Harte & Lyne Limited http://www.harte-lyne.ca > 9 Brockley Drive vox: +1 905 561 1241 > Hamilton, Ontario fax: +1 905 561 0757 > Canada L8E 3C3 > > _______________________________________________ > CentOS mailing list > CentOS at centos.org > http://lists.centos.org/mailman/listinfo/centos > -- ---~~.~~--- Mike // SilverTip257 //