[CentOS] Re: RAID, LVM, extra disks...

[Ross S. W. Walker]

Ugo Bellavance wrote:
> 
> Alain Spineux wrote:
> > On Nov 29, 2007 4:21 PM, Ugo Bellavance <ugob at lubik.ca> wrote:
> >> Alain Spineux wrote:
> >>> On Nov 29, 2007 6:59 AM, Ugo Bellavance <ugob at lubik.ca> wrote:
> >>>> Hi,
> >>>>
> >>>>         This is my current config:
> >>>>
> >>>> /dev/md0 -> 200 MB -> sda1 + sdd1 -> /boot
> >>>> /dev/md1 ->  36 GB -> sda2 + sdd2 -> form VolGroup00 with md2
> >>>> /dev/md2 ->  18 GB -> sdb1 + sde1 -> form VolGroup00 with md1
> >>>>
> >>>> sda,sdd -> 36 GB 10k SCSI HDDs
> >>>> sdb,sde -> 18 GB 10k SCSI HDDs
> >>>>
> >>>> I have added 2 36 GB 10K SCSI drives in it, they are detected as 
> >>>> sdc and sdf.
> >>>>
> >>>> What should I do if I want to optimize disk space?
> >>>>
> >>>> The simplest solution would be to create /dev/md3 out of 
> sdc1 and 
> >>>> sdf1, and add it to the VG, and increase the size of my 
> /vz logical volume.
> >>>>
> >>>> However, if I could convert that to a RAID5 (it could be 
> possible 
> >>>> to re-install, but I would rather not), I could have 6 drives in 
> >>>> RAID5, so I'd have 5x36 GB (180) of space available 
> total, instead of 3*36 (108).
> >>> 180, you mean 2 X 5x18
> >> Oh, I just realized I have 2X18 and 4X36.  I have 2 other 
> 36 GB HDD 
> >> here.  Maybe I could have a 6x36 RAID5 this way.  Does it 
> matter if I
> > 
> > drop the 2x18, to drop the 2x18 complexity, or keep them in 
> mirroring, 
> > and maybe on another VG, to backup/store more critical data
> 
> Ok, but the server can only have 6 HDD.
> 
> So, first step, how would I replace the current 2X18 by the 
> 2x36 that I put in the server yesterday?
> 
> (BTW thanks a lot for your help, it is very interesting)

If you wanted to reconfigure this all online it could be done,
but it will be tricky depending on your current LV allocations
and layout.

-Ross

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