On Nov 16, 2011, at 7:35 AM, David Dyer-Bennet wrote: > > On Tue, November 15, 2011 17:05, Anatoly wrote: >> Good day, >> >> The speed of send/recv is around 30-60 MBytes/s for initial send and >> 17-25 MBytes/s for incremental. I have seen lots of setups with 1 disk >> to 100+ disks in pool. But the speed doesn't vary in any degree. As I >> understand 'zfs send' is a limiting factor. I did tests by sending to >> /dev/null. It worked out too slow and absolutely not scalable. >> None of cpu/memory/disk activity were in peak load, so there is of room >> for improvement. > > What you're probably seeing with incremental sends is that the disks being > read are hitting their IOPS limits. Zfs send does random reads all over > the place -- every block that's changed since the last incremental send is > read, in TXG order. So that's essentially random reads all of the disk.
Not necessarily. I've seen sustained zfs sends in the 600+ MB/sec range for modest servers. It does depend on how the data is used more than the hardware it is stored upon. -- richard -- ZFS and performance consulting http://www.RichardElling.com LISA '11, Boston, MA, December 4-9 _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
