[CentOS] Advice on partitioning a Dell MD1200 disk array

Wed Sep 5 19:46:18 UTC 2012
Dean Jones <dean.jones at oregonstate.edu>

On Wed, Sep 5, 2012 at 12:02 PM, Tony Molloy <tony.molloy at ul.ie> wrote:
> On Tuesday 04 September 2012 15:20:26 Paul Tader wrote:
>> > The second MD1200 will be used to backup the first, using
>> > BackupPC and for other storage purposes.
>> >
>> > As I won't know the storage requirements for the "backup
>> > partition" and they will probably change over time anyway. I was
>> > thinking of using LVM for it. So how to partition the MD1200 for
>> > LVM. I don't want to put all 12 disks in  a RAID5 and put a LVM
>> > volume on it. Can I split it into 2 RAID5 and have a LVM volume
>> > spanning both.
>> Just a thought about the backup volume.
>> Because it going to be used for backups and your retirement
>>  (congrats!) I would configure one partition and no volume
>>  management on top.  Why? Because backups are like insurance
>>  policies.  That are not fun and no one reviews them, but when you
>>  need them, you really hope that everything is in order.  So you
>>  don't want the next admin to find out several months or years down
>>  the road that the backup software ran out of space and has been
>>  failing to back anything up for the previous few months.
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> Thanks to Gotz, Blake, Paul and Nate for your advice.
> I was pretty happy with the split RAID 5 for the NFS partitions on the
> first MD1200.
> I think I'll go with the simple solution for the backup MD1200. A
> single RAID 5 encompassing all 12 disks probably with 2 hot spares.
> Put an ext4 on top of that without the complexity of LVM.
> Thanks,
> Tony
> aside Paul, unfortunately my retirement is not voluntary. It's due to
> a spinal cord injury but such is life ;-)

I would highly suggest RAID 6 if you are dealing with drives over 2TB
in size.  Errors during rebuild happen and rebuild times for 2TB+
drives can get pretty long, especially if you are building one 12 disk

Also important if a non-savvy admin is going to take over
administration.  What if they pull the wrong drive during a
replacement on a failed RAID5 array?