hi
i created a snapshot of a lvm, like this:
lvcreate -s -L +50G -p r -n backup /dev/mail/mail /dev/sda2
that is, a 50gb, read-only snapshot for /dev/mail/mail to the PV sda2.
the i did a lvdisplay -v
--- Logical volume ---
LV Name /dev/mail/mail
VG Name mail
LV UUID jhjDsx-FvKT-zJer-uSc3-2rrb-eHaC-Af7jBq
LV Write Access read/write
LV snapshot status source of
/dev/mail/backup [active]
LV Status available
# open 1
LV Size 150.22 GB
Current LE 4807
Segments 1
Allocation next free (default)
Read ahead sectors 0
Block device 254:3
--- Logical volume ---
LV Name /dev/mail/backup
VG Name mail
LV UUID nQrrrx-cTN8-4lqX-op9F-1vDO-VJ1V-hbQlTU
LV Write Access read only
LV snapshot status active destination for /dev/mail/mail
LV Status available
# open 0
LV Size 150.22 GB
Current LE 4807
Segments 1
Snapshot chunk size 8.00 KB
Allocated to snapshot 0.13%
Allocation next free (default)
Read ahead sectors 0
Block device 254:6
how can i tell, how big is that snapshot i created? i know that it's
50gb, but where can i see this information. and what is "Allocated to
snapshot"? that percentage is from the 50gb a allocated for the
snapshot? or from the origin LV ?
lvm> version
LVM version: 2.00.15 (2004-04-19)
Library version: 1.00.14-ioctl (2004-04-06)
Driver version: 4.4.0
i installed lvm from CVS too, and i noticed the output of lvdisplay is a
bit different there. in fact, lvdisplay does not even show the snapshot
LV i created... if i do a vgdisplay -v, only then appears:
--- Logical volume ---
LV Name /dev/test/root
VG Name test
LV UUID wqoG5m-X3Fn-Gsaj-8P9t-cSwS-AXi4-IJ5j2P
LV Write Access read/write
LV snapshot status source of
/dev/test/backup_root [active]
LV Status available
# open 1
LV Size 976.00 MB
Current LE 244
Segments 1
Allocation inherit
Read ahead sectors 0
Block device 253:3
--- Logical volume ---
LV Name /dev/test/backup_root
VG Name test
LV UUID cHs3wn-EUJl-f1wq-R8SJ-kpxZ-u9CG-L9Qhy1
LV Write Access read only
LV snapshot status active destination for /dev/test/root
LV Status available
# open 0
LV Size 976.00 MB
Current LE 244
COW-table size 1016.00 MB
COW-table LE 254
Allocated to snapshot 2.05%
Snapshot chunk size 8.00 KB
Segments 1
Allocation inherit
Read ahead sectors 0
Block device 253:2
lvm> version
LVM version: 2.01.13-cvs (2005-06-14)
Library version: 1.01.01 (2005-03-29)
Driver version: 4.4.0
what's COW? :)
thx.
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