[linux-lvm] Any way to speed up activation of volumes with snapshots?

[Zdenek Kabelac]

Dne 14.9.2015 v 20:05 Chris Friesen napsal(a):
> Hi,
>
> I'm running a 3.10 kernel with LVM 2.02.95.
>
> I'm running into a problem where activating snapshots can take quite a long
> time, roughly one minute per 25GB of delta between the snapshot and the origin
> volume.  (See below for my test procedure.)
>
> I realize that my kernel/LVM aren't exactly bleeding edge, and I wondering
> whether more recent versions have done anything to speed up the activation
> process (like maybe making it more lazy-loaded rather than reading in a bunch
> of data up-front).
>
> If anyone is aware of such improvements, I'd appreciate it if you could point
> me at the appropriate changes.

Hi

There is NO way to accelerate your existing setup, other then placing delta on 
SSD - the format of snapshot was meant to be used 'temporarily' - i.e. until 
you take backup of LV - but not for long-term multi-gigabyte case.

This is major mis-use of this 'snapshot' feature - which repeats over and over...

If you want to use long-living snapshots - you need to use thin-provisioning,
.
> The final "lvchange" command took about 4m22s.  This works out to 362MB/sec,

I've seen users waiting even 1/2 hour - so you are still 'lucky' user ;)



Zdenek