On 07/25/11 04:21 AM, Roberto Waltman wrote:
Edward Ned Harvey wrote:
> So I'm getting comparisons of write speeds for 10G files, sampling
at 100G
intervals. For a 6x performance degradation, it would be 7 sec to write
without dedup, and 40-45sec to write with dedup.
For a totally unscientific data point:
The HW: Server - Supermicro "server" motherboard.
Intel 920 CPU.
6 GB memory.
1 x 16 GB SSD as a boot device.
8 x 2TB "green" (5400 RPM?) hard drives.
The disks configured with 3 equal size partitions, all p1's in one
raidz2 pool, all p2's in another, all p3's in another.
(Done to improve performance by limiting head movement when most of the
disk activity is in one pool)
The SW: the last release of Open Solaris. (Current at the time, I have
since moved to Solaris 11)
The test: backup an almost full 750Gb external hard disk formatted as a
single NTFS volume. The disk was connected via eSATA to a fast computer
(also a supermicro + I920) running Ubuntu.
The Ubuntu machine had access to the file server via NFS.
The NFS-exported file system was created new for this backup, with dedup
enabled, encryption and compression disabled, atime=off. This was the
first (and last) time I tried enabling dedup.
From previous similar transfers, (without dedup), I expected the backup
to be finished in a few hours overnight, with the bottlenecks being the
NTFS-3G driver in Ubuntu and the 100Mbit ethernet connection.
It took more than EIGHT DAYS, without any other activity going on both
machines.
(My) conclusion: Running low on storage? get more/bigger disks.
Add to that: if running dedup, get plenty of RAM and cache.
I'm still seeing similar performance on my test system with and without
dedup enabled. Snapshot deletion appears slightly slower, but I have
yet to run timed tests.
--
Ian.
_______________________________________________
zfs-discuss mailing list
zfs-discuss@opensolaris.org
http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
