[mythtv-users] Migrating RAID

John Drescher drescherjm at gmail.com
Thu Nov 1 14:21:49 UTC 2007

> Well, part of the motivation is "because I can"... :-)
> But it's also because I'd like to test just how robust 'growing an
> array' really is.
I did some testing on this 2 weeks ago on with 8 new 750GB sata disks.
I started out and created a software raid 5 array using only 4 of the
disks with xfs as the file system. Then I used mdadm to add 1 drive at
a time and in between each iteration I grew the xfs filesystem. I can
say one thing though. This operation is slow as the rebuild time for
adding a single drive was many hours and even longer than creating an
8 drive raid 6 array.

Also during the operation mdadm writes a special file to a
disk/partition not used in the array so that if something goes wrong
it is supposed to be able to use this to continue the operation. I did
not have time to see if a power failure during the reshape would cause
data loss or mdadm would pick up where it left off.

> You can supposedly grow an array while it's live.
Yes, this worked very well. But this was only a single test of a few
reshapes from 1 user on one kernel version. In my case I believe it
was a 32 or 64 bit gentoo 2007.0 livecd.



More information about the mythtv-users mailing list