[CentOS] Software Raids Questions (I have only ever used hardware?)

Karanbir Singh mail-lists at karan.org
Mon Sep 28 00:56:45 UTC 2009


On 27/09/09 21:32, aurfalien at gmail.com wrote:
> few things;
>
> i'm not hip to the latest barney phife shareware utils that may allow
> some kind of dynamic raiding bs, but generally, no, you must format
> those drive to the desired fs after raiding them so back up all data u
> want housed (or hozed) on that new raid.

This is not true. Even with the extremely basic process, you only need 
to have 1 disk in 'being prepd' state - which means you can, if there is 
time and resources, shovel data around on the disks as they get used 
into the raid setup. Ofcourse, you will need to have 1 disk clear.

Eg. to convert this setup into a raid-5 : start with a 1 disk raid-1 
degraded, move a disks worth of data onto there, bring in the second 
disk and let them sync into a 'normal' raid1 state, then convert that 
into a raid-5 with the 3rd disk. then bring in the 4th disk as hotspare.

with TiB's worth of data, its not going to be quick.

- KB



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