[CentOS] First Time Setting up RAID

Thu Nov 14 17:43:18 UTC 2013
m.roth at 5-cent.us <m.roth at 5-cent.us>

James B. Byrne 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
> 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
> more that I should but do not know enough yet to ask.
>>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

Why? Where did you get that idea? On all of our large RAIDs, we're using
RAID 6 - remember, with RAID 1, you have half the space of the physical

> had by taking two of the 8 drives (6Tb) solely to hold the OS and boot

Are you doing Linux software RAID, or do you have a hardware RAID controller?

Me, I'd partition it up... lessee, the 3TB drive that I'm about to replace
one of our user's root drive has 1G /boot, 2G swap, 500G /, and a 4th
partition with the rest of the space.
> 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
> that RAID 5 is the only viable option.  It also appears that the amount of

Sounds old news, to me. As I said *all* of our large RAIDs are running 6.

> As the amount of disk space we have in this unit (24Tb) is greater than

Note that I'd make it 14TB and 10TB, or perhaps 500G, maybe RAID 1, for a
total of 1TB, then 14TB and 9TB.

> 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.

Yeah, a hot spare's a good idea.