Re: [PATCH 0/3] add resync speed control for dm-raid1

[Lars Marowsky-Bree <lmb@suse.de>]

On 2012-12-10T13:21:23, NeilBrown <neilb@suse.de> wrote:

> The problem with this approach is that it slows down resync even when there
> is no other IO happening.
> If that is deemed to be acceptable, then the patch set seems fine, though I
> would probably make the default a lot higher so as not to change current
> default behaviour for anyone.

I agree to the latter part.

The difficulty is that our primary use case here is preventing IO
starvation while cluster raid is resyncing; and we don't know the IO
load on other nodes, or what other LVs might inflict on the same backend
store / PV. Hence, a static limit probably is the easiest way to
start.

I agree that a more dynamic approach would be desirable, but that
appears to be very complex to get right.


Thanks,
    Lars

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