[linux-lvm] Reserve space for specific thin logical volumes
zren at suse.com
Mon Sep 11 21:35:53 UTC 2017
> lvm2 is using upstream community BZ located here:
> You can check RHBZ easily for all lvm2 bZ
> (mixes RHEL/Fedora/Upstream)
> We usually want to have upstream BZ being linked with Community BZ,
> but sometimes it's driven through other channel - not ideal - but
> still easily search-able.
Yes, it's a place where problems are discussed. Thanks for your reminder :)
> It's should be opposite case - unless something regressed recently...
> Easiest is to write out lvm2 test suite some test.
> And eventually bisect which commit broke it...
Good to know! I will find time to test different versions on both
openSUSE and Fedora.
>> - pvmove is slow. I know it's not fault of LVM. The time is almost
>> spent in DM (the IO dispatch/copy).
> Yeah - this is more or less design issue inside kernel - there are
> some workarounds - but since primary motivation was not to overload
> system - it's been left a sleep a bit - since focus gained 'raid' target
Aha, it's a good reason. Ideally, it would be good for pvmove having
some option to control
the IO rate. I know it's not easy...
> and these pvmove fixes are working with old dm mirror target...
> (i.e. try to use bigger region_size for mirror in lvm.conf (over 512K)
> and evaluate performance - there is something wrong - but core mirror
> developer is busy with raid features ATM....
Thanks for the suggestion.
>> - snapshot cannot be used in cluster environment. There is a usecase:
>> user has a central backup system
> Well, snapshot CANNOT work in cluster.
> What you can do is to split snapshot and attach it different volume,
> but exclusive assess is simply required - there is no synchronization
> of changes like with cmirrord for old mirror....
Got it! Advanced features like snapshot/thinp/dmcache, have their own
metadata. The payment for having those metadata
changes cluster-aware is painful.
> We do our best....
Like you guys have been always doing, thanks!
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