On Wed, Jan 7, 2009 at 12:36 AM, Andrew Gabriel <andrew.gabr...@sun.com> wrote: > Brent Jones wrote: > >> Reviving an old discussion, but has the core issue been addressed in >> regards to zfs send/recv performance issues? I'm not able to find any >> new bug reports on bugs.opensolaris.org related to this, but my search >> kung-fu may be weak. > > I raised: > CR 6729347 Poor zfs receive performance across networks > (Seems to still be in the Dispatched state nearly half a year later.) > > This relates mainly to full archives, and is most obvious when > the disk throughput is the same order of magnitude as the network > throughput. (It becomes less obvious if one is significantly > different from the other, either way around.) > > There appears to be an additional problem for incrementals, which > spend long periods sending almost no data at all (I presume this > is when zfs send is searching for changed blocks to send). > I don't know off-hand of a bugid for this. > >> Using mbuffer can speed it up dramatically, but this seems like a hack >> without addressing a real problem with zfs send/recv. > > I don't think it's a hack, but something along these lines should > be more properly integrated into the zfs receive command or > documented. > >> Trying to send any meaningful sized snapshots from say an X4540 takes >> up to 24 hours, for as little as 300GB changerate. > > Are those incrementals from a much larger filesystem? > If so, that's probably mainly the the other problem.
Yah, the incrementals are from a 30TB volume, with about 1TB used. Watching iostat on each side during the incremental sends, the sender side is hardly doing anything, maybe 50iops read, and that could be from other machines accessing it, really light load. The receiving side however, for about 3 minutes it is peaking around 1500 iops reads, and no writes. It will do that for 3-5 minutes, then it will calm down and only read sporadically, and write about 1MB/sec. Using Mbuffer can get the writes to spike to 20-30MB/sec, but the initial massive reads still remain. I have yet to devise a script that starts Mbuffer zfs recv on the receiving side with proper parameters, then start an Mbuffer ZFS send on the sending side, but I may work on one later this week. I'd like the snapshots to be sent every 15 minutes, just to keep the amount of change that needs to be sent as low as possible. Not sure if its worth opening a case with Sun since we have a support contract... > > -- > Andrew > -- Brent Jones br...@servuhome.net _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
