[CentOS] C5 64-bit and software RAID 6?

[Scott R. Ehrlich]

On Sat, 8 Mar 2008, Rudi Ahlers wrote:

>
>
>
> On Sat, March 8, 2008 19:18, Mogens Kjaer wrote:
> Scott R. Ehrlich wrote:
>> I have a Dell PowerEdge 2950 with 6 SAS disks and a PERC 5/i controller
>> what won't do RAID 6.  I plan to have 2 drives as RAID 1 for the OS, and
>> the remaining 4 as RAID 6.  Granted the PERC can do RAID 1, I'm tempted
>> to do everything via software RAID.  Thus, if anything goes wrong with
>> the controller, I just need to obtain a new SAS controller and I'm back
>> up.
>
> 4 disks in RAID 6? Isn't this a bit overkill? You would use half
> the space for RAID checksums.
>
> If it were me, I would:
>
> Partition all drives identically with a 200M partition 1
> and the rest as partition 2
>
> Use sda1 and sdb1 in RAID 1 as /boot
> Use sd[cdef]1 as swap in RAID 5
> Use sd[abcdef]2 as / in RAID 5
>
> You could use RAID 6 for /, but then you're not 100%
> safe if you loose disks 1 and 2 simultaneously.
>
> Mogens
>
> --
> Mogens, RAID 5 can only handle 1 drive failure. So, if he had 3 drives in
> he set & 1 spare, then that 1 spare will be used to rebuild te stripe,
> which could take long if it's big. If something goes wrong during this
> period, he could effectivly loose all his data. So he'll be as screwed
> (sorry, I couln't think of a better word) as if he had to loose 2 drives
> in RAID 6 stripe
>
> RAID 6 with 4 drives will give the same volume, since all 4 drives are
> used, but offers 2 drive failure.
>
> I would suggest rather use RAID 10 (this is 2x RAID 1 stripes, stripped
> together as RAID 0), as it will give you better performance and will be
> much more reliable

What would be the recommended way to create a software RAID 10 array?

Again, two disks for the OS as s/w RAID 1, the remaining four disks for 
data as RAID 10, with possibly 1 of the 4 as a [hot] spare.

Thanks.

Scott

>
>
> -- 
>
> Kind Regards
> Rudi Ahlers
> CEO, SoftDux
> Website: http://www.SoftDux.com
> Forums:  http://Forum.SoftDux.com
>
>
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