Hello List,
I'm happy to be able to say that the problem seems to be solved.
The upgrade from 7.0.4 to 7.0.5 did not improve the performance of Qtree Snapmirroring (about the same 30 minutes). But today after converting to VSM I was really impressed.
The initial sync of 170 GB (incl. snapshots) took about 170 minutes which is MUCH better than before. I remember about 16 hours or even more.
After that the differential transfers took took about 1-3 minutes for a schedule of 10 minutes.
I switched to synchrous for test and DID NOT see the expected performance disaster. Our mailserver did not notice any difference. Of course I will do some measurements in future but for now I left it in the sync. state. Perhaps I will have to switch to semi-sync or even back to async but the problem itself seems to have gone away!!!
Thanks for all helpful hints, thomas
On Fri, 29 Dec 2006, Thomas Bleek wrote:
Hello,
I wonder what transferrate I could expect for snapmirror volumes (an/or qtrees) between 2 FAS270 directly connected with Gigabit Ethernet.
We use one filer as NFS backing store for our Mailsystem (Communigate Pro) with mdir mailbox format, so we have many small files here.
I see abnormal high lags with really moderate sizes of the transferred data.
For instance we need about 20 to 40 minutes to transfer 100 to 600 MBytes!
The filesystems a 50% filled 250 GByte Volume/qtree with 10.3 million files (with 7 mio free inodes).
so the average filesize is about 12KByte.
We use Ontap 7.0.4 here and will upgrade to 7.0.5 next week. But I don't really have much hope that this will change the problem.
Could anybody give me some data about his/her transfer rates? I really can't believe, that this slow transfers are normal.
An repeatedly snapmirror status command on the filer shows this:
at first the transfer startet and transferred about 68 MByte in 80 seconds. after that it paused for 15 minutes (output constantly "transferring 68MB done"). from minute 16 to 26 it says "transferring inodes". in these 11 minutes it transferred 225.000 inodes. after that it transfers data again. in minute 28 it has transferred 550 MBytes. after that one minute pause and then the status is idle.
Has netapp/snapmirror a big problem with small files? I don't want to switch to mailbox format because I like the advantages of mdir (single copy mailstore, easier backup?)
Thanks for any hints, thomas
Dr. Thomas Bleek, Netzwerkadministrator GeoForschungsZentrum Potsdam,Rechenzentrum,Telegrafenberg G261,D-14473 Potsdam Tel.: +49 331 288- 1818/1681 Fax.: 1730 Mobil: +49 172 1543233 E-Mail: bl@gfz-potsdam.de