[CentOS] Re: RAID, LVM, extra disks...
ugob at lubik.ca
Thu Nov 29 15:21:38 UTC 2007
Alain Spineux wrote:
> On Nov 29, 2007 6:59 AM, Ugo Bellavance <ugob at lubik.ca> wrote:
>> 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
>> 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
have 4 HDD that are 10K and 2 7200 rpm?
What about raid 6? I don't think I need fault tolerance for 2 HDD
> Yes and without rebooting :-)
> - break the 36GB mirror (using mdadm, faile /dev/sdd2, and then remove it),
> - break the 18GB mirror (using mdadm, faile /dev/sde1, and then remove it),
> - create sd[cf] of 200Mb, 18G, 18G (the 200Mb is useless but to
> keep the same partitioning schema)
> - create a _degraded_ raid5 with sd[cfd]2 sde1 named /dev/mdX
> - vgextend your VolGroup00 to use this new partition.
> # pvcreate /dev/mdX
> # vgextend VolGroup00 /dev/mdX
> - then move all PE on md1 to mdX
> # pvmove /dev/md1/dev/mdX
> - then remove md1 from the VG
> # vgreduce VolGroup00 /dev/md1
> - now you dont need md1 anymore, stop it (sorry I'm less skilled with
> mdadm command, without manual page )
> - now add /dev/sda2 to your _degraded_ raid 5
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