[linux-lvm] lvm-vdo, snapshots and cache
zdenek.kabelac at gmail.com
Tue Nov 15 21:56:01 UTC 2022
Dne 15. 11. 22 v 18:42 Gionatan Danti napsal(a):
> Dear all,
> as previous vdo utils are gone in RHEL9, VDO volumes must be created via
> lvm-vdo and associated lvm commands.
> What is not clear to me is how to combine lvm-vdo with lvmthin (for fast CoW
> snapshots) and/or lvmcache (for SSD caching of an HDD pool). For example, with
> the old /dev/mapper/vdo style volumes (ie: the one created via vdo create) one
> can do something as physical_dev -> vdo -> lvmthin -> lvmcache.
> How to do the same with lvm-vdo?
You could try 'vg' on top of another 'vg' - however I'd not recommend to use
it this way (and it's unssuported (&unsupportable) by lvm2 in general)
We aim to support multiple VDO LV within a single VDOPOOL - will hopefully
happen relatively soon (so it should work like with thin pools)
IMHO I'd not recommend to combine 2 provisioning technologies - it's already
hard to resolve 'out-of-space' troubles with just one technology...
We will see if the 'VDO thick snapshot' will also go with multiple VDO LV
support - likely not - but will be added later on.
Caching should be already support - on VDO LV as well as on VDOPOOL LV (both
work somewhat differently).
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