Stuff

New Linux Device Mapper Snapshot Performance

Here’s a quick weigh-in on the new experimental device-mapper thin provisioning (and improved snapshots) that exists in linux kernel 3.2. I recently compiled a kernel and tested it, and it looks rather promising. I would expect this to become stable more quickly than, say, btrfs (which obviously has different design goals but could also be used as a means of snapshotting files/vm disks). With any luck, LVM will be fitted for support relatively soon.

These are quick and dirty, sequential write test was with ‘dd if=/dev/zero of=testfile bs=1M count=16000 conv=fdatasync’, and results are in MB/s. ¬†Random IO test was done with fio:
[global]
ioengine=libaio
iodepth=4
invalidate=1
direct=1
thread
ramp_time=20
time_based
runtime=300

[8RandomReadWriters]
rw=randrw
numjobs=8
blocksize=4k
size=512M

 

At any rate, it looks like we’re well on our way to high performance LVM snapshots that work well ¬†(finally!).

 

 

Leave a Reply

Your email address will not be published. Required fields are marked *