Hi.
I'm experiencing a LVM (dm) hang during a live volume snapshot creation.
I'm using FC4 with a custom built 2.6.12 kernel on a dual P_III 1.3 GHz /
1GB RAM / 1 IDE ATA HDD.
I started a 'dd':
----
dd if=/dev/urandom of=/lvm_part/file.oput bs=1M count=3000
----
After cca. 200 MB were written, I started creating snapshots of the
mentioned volume:
----
i=1
while ((i<=20)); do
lvcreate -s -L 320M -n s${i} -p r /dev/vg00/test01
let i=i+1
done
----
The affected LVM volume + underlying 'dm' freezed during creation of the
5th snapshot - afterwards any I/O on the affected volume freeze too (e.g.
'echo blabla > /lvm_part/file.out' (only 'ls' was still working). Any
'LVM' command for the affected volume group (e.g. 'lvscan',
'vgdisplay',...) freeze too.
I/O on a volume in the same volume group was still working.
I had to reboot to solve the problem.
I found some threads with similar problems:
- https://www.redhat.com/archives/dm-devel/2005-February/msg00009.html
- http://marc.theaimsgroup.com/?t=110507495500002&r=1&w=2
I guess my problem is related to the above threads, however it seams it is
not exactly the same - it seams to me that I'm not going out of memory
(see below).
Do anyone have a hint what's going on? Is there any kernel patch that fix
the mentioned problem? If not ... any hint where should I start? << I
have to fix the problem :)
# cat /proc/slabinfo | head -2; cat /proc/slabinfo |grep -e dm -e jour -e
bio -e ext3
slabinfo - version: 2.1
# name <active_objs> <num_objs> <objsize> <objperslab>
<pagesperslab> : tunables <limit> <batchcount> <sharedfactor> : slabdata
<active_slabs> <num_slabs> <sharedavail>
dm-snapshot-in 128 162 48 81 1 : tunables 120 60 8
: slabdata 2 2 0
dm-snapshot-ex 1981 2260 16 226 1 : tunables 120 60 8
: slabdata 10 10 0
dm_tio 4574 4746 16 226 1 : tunables 120 60 8
: slabdata 21 21 0
dm_io 4574 4746 16 226 1 : tunables 120 60 8
: slabdata 21 21 0
journal_handle 32 185 20 185 1 : tunables 120 60 8
: slabdata 1 1 0
journal_head 265 1350 52 75 1 : tunables 120 60 8
: slabdata 18 18 0
ext3_inode_cache 756 763 508 7 1 : tunables 54 27 8
: slabdata 109 109 0
ext3_xattr 118 176 44 88 1 : tunables 120 60 8
: slabdata 2 2 0
biovec-(256) 264 264 3072 2 2 : tunables 24 12 8
: slabdata 132 132 0
biovec-128 272 275 1536 5 2 : tunables 24 12 8
: slabdata 55 55 0
biovec-64 288 290 768 5 1 : tunables 54 27 8
: slabdata 58 58 0
biovec-16 288 300 192 20 1 : tunables 120 60 8
: slabdata 15 15 0
biovec-4 288 305 64 61 1 : tunables 120 60 8
: slabdata 5 5 0
biovec-1 732 1582 16 226 1 : tunables 120 60 8
: slabdata 7 7 0
bio 732 1558 96 41 1 : tunables 120 60 8
: slabdata 38 38 0
# cat /proc/meminfo
MemTotal: 906280 kB
MemFree: 557632 kB
Buffers: 30008 kB
Cached: 264500 kB
SwapCached: 0 kB
Active: 68044 kB
Inactive: 249244 kB
HighTotal: 0 kB
HighFree: 0 kB
LowTotal: 906280 kB
LowFree: 557632 kB
SwapTotal: 1048816 kB
SwapFree: 1048816 kB
Dirty: 36 kB
Writeback: 888 kB
Mapped: 31732 kB
Slab: 18700 kB
CommitLimit: 1501956 kB
Committed_AS: 59292 kB
PageTables: 600 kB
VmallocTotal: 122824 kB
VmallocUsed: 2536 kB
VmallocChunk: 114632 kB
HugePages_Total: 0
HugePages_Free: 0
Hugepagesize: 4096 kB
Thanks and best regards,
Dezo
