[lvm-devel] [PATCH 0 of 13] LVM add 'mirrored' log type
Takahiro Yasui
tyasui at redhat.com
Mon Feb 22 09:18:35 UTC 2010
Jonathan Brassow wrote:
> I'm also testing the other approach; that is, allowing lvconvert to take
> non-top-level LVs (e.g. "lv_mlog"). It seems to work just fine. We
> might want to strongly consider allowing this.
>
> There are drawbacks to this approach too, however. For example, when
> one of the devices of the log fails, it will be treated as an 'image'
> failure, and not a 'log' failure (I can fix that though by checking its
> lv->status). If we decide to go this route, we will have to decide if
> this is the behavior we want or not. (Once the log is linear, it will
> behave as you would expect - either being replaced or removed according
> to the log policy.)
This approach requires two threads in dmeventd; it is for a top-level LV,
and another is for a mirrored log. If a leg and mirrored log failed at
the same time, a mirrored log needs to be recovered before a top-level LV.
I think this approach is also good if we can handle this situation.
Thanks,
Taka
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