[linux-lvm] Testing the new LVM cache feature
Richard W.M. Jones
rjones at redhat.com
Thu May 22 15:22:32 UTC 2014
Well I'm happy to experiment for you.
At the moment I'm stuck here:
# vgcreate vg_cache /dev/sdc1
Volume group "vg_cache" successfully created
# lvcreate -L 1G -n lv_cache_meta vg_cache
Logical volume "lv_cache_meta" created
# lvcreate -L 229G -n lv_cache vg_cache
Logical volume "lv_cache" created
# lvs
LV VG Attr LSize [...]
lv_cache vg_cache Cwi---C--- 229.00g
lv_cache_meta vg_cache -wi-a----- 1.00g
testoriginlv vg_guests -wi-a----- 100.00g
# lvconvert --type cache-pool --poolmetadata /dev/vg_cache/lv_cache_meta /dev/vg_cache/lv_cache
Logical volume "lvol0" created
Converted vg_cache/lv_cache to cache pool.
# lvs
LV VG Attr LSize [...]
lv_cache vg_cache Cwi---C--- 229.00g
testoriginlv vg_guests -wi-a----- 100.00g
# lvconvert --type cache --cachepool vg_cache/lv_cache vg_guests/testoriginlv
Unable to find cache pool LV, vg_cache/lv_cache
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
It seems as if vg_cache/lv_cache is a "cache pool" but for some reason
lvconvert is unable to use it.
The error seems to come from this code:
if (!(cachepool = find_lv(origin->vg, lp->cachepool))) {
log_error("Unable to find cache pool LV, %s", lp->cachepool);
return 0;
}
Is it looking in the wrong VG?
Or do I have to have a single VG for this to work? (That's not made
clear in the documentation, and it seems like a strange restriction).
Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
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