On Sun, 2010-10-24 at 15:48 -0400, Bob Ball wrote:> We may need to completely empty an OST, so that we can more efficiently
> format the underlying RAID-6 array (in light of recent discussions about
> the stripe on this list). What is the most efficient way to do this? I
> can use multiple clients running lfs_migrate from pre-prepared lists,
> but that will likely be a relatively slow process. Are there other,
> perhaps better ways to do this?
If you have enough free space to duplicate the OST you could do a
byte-level copy of it, bringing it up on a completely new device.
But if you don''t have that space available, lfs_migrate is about your
best choice. Even with the excellent lfs_migrate script I would
strongly advise you be familiar with what lfs_migrate is doing and the
general process of object migration and at every step, "measure twice,
cut once".
When I do things like this, I typically spend many times as much time
verifying that my previous step was successful and what my next step
will be than I spend actually doing the steps.
Probably, similarly to how you describe using lists of objects on
multiple clients, lfs_migrate could be made to scale by using multiple
co-ordinated clients. We always gladly accept patches. :-)
Cheers,
b.