On 12-05-07 12:18 PM, Jim Klimov wrote:
During the send you can also monitor "zpool iostat 1" and usual
"iostat -xnz 1" in order to see how busy the disks are and how
many IO requests are issued. The snapshots are likely sent in
the order of block age (TXG number), which for a busy pool may
mean heavy fragmentation and lots of random small IOs..
I have been able to verify that I can get a zfs send at 135MB/sec for a striped pool with 2 internal drives on the same server.


Each dataset had about 3-4 snapshots. There were about 36 datasets

I deleted the snapshots and the speed may have increased slightly.

Given "iostat -xnz 1" it looks like the IO's are very high. So I guess the drives are badly fragmented.

So is fixing this going to require a zfs pool rebuild?

Karl

                    extended device statistics
    r/s    w/s   kr/s   kw/s wait actv wsvc_t asvc_t  %w  %b device
0.0 4.0 0.0 16.0 0.0 0.0 0.0 0.0 0 0 c0t500151795955D430d0 0.0 4.0 0.0 16.0 0.0 0.0 0.0 0.0 0 0 c0t500151795955BDB6d0 0.0 1.0 0.0 8.0 0.0 0.0 0.0 0.1 0 0 c0t5001517BB271845Dd0 759.0 0.0 4800.0 0.0 0.0 2.9 0.0 3.8 0 75 c0t5000C500103F2057d0 887.0 0.0 4738.0 0.0 0.0 1.6 0.0 1.8 0 42 c0t5000C500103E9FFBd0 915.0 0.0 4628.5 0.0 0.0 1.5 0.0 1.6 0 30 c0t5000C5000440AA0Bd0 922.0 0.0 4676.5 0.0 0.0 1.0 0.0 1.1 0 26 c0t5000C500103E120Fd0 970.0 0.0 4276.0 0.0 0.0 1.0 0.0 1.0 0 20 c0t5000C500103E370Fd0
                    extended device statistics
    r/s    w/s   kr/s   kw/s wait actv wsvc_t asvc_t  %w  %b device
0.0 4.0 0.0 32.0 0.0 0.0 0.0 0.1 0 0 c0t5001517BB271845Dd0 1363.0 0.0 9007.8 0.0 0.0 2.0 0.0 1.5 1 54 c0t5000C500103F2057d0 1405.0 0.0 10169.2 0.0 0.0 1.8 0.0 1.3 1 37 c0t5000C500103E9FFBd0 1448.0 0.0 9884.2 0.0 0.0 1.7 0.0 1.2 1 40 c0t5000C5000440AA0Bd0 1264.0 0.0 9537.3 0.0 0.0 2.1 0.0 1.7 0 51 c0t5000C500103E120Fd0 1260.0 0.0 9749.8 0.0 0.0 1.9 0.0 1.5 0 44 c0t5000C500103E370Fd0
                    extended device statistics
    r/s    w/s   kr/s   kw/s wait actv wsvc_t asvc_t  %w  %b device
0.0 6.0 0.0 24.0 0.0 0.0 0.0 0.0 0 0 c0t500151795955D430d0 0.0 6.0 0.0 24.0 0.0 0.0 0.0 0.0 0 0 c0t500151795955BDB6d0 1023.0 0.0 5131.6 0.0 0.0 1.6 0.0 1.6 0 45 c0t5000C500103F2057d0 1003.0 0.0 5040.1 0.0 0.0 1.5 0.0 1.5 0 36 c0t5000C500103E9FFBd0 959.0 0.0 5069.1 0.0 0.0 1.7 0.0 1.8 0 46 c0t5000C5000440AA0Bd0 941.0 0.0 5117.6 0.0 0.0 1.7 0.0 1.8 0 45 c0t5000C500103E120Fd0 1043.0 0.0 5034.1 0.0 0.0 1.0 0.0 1.0 0 24 c0t5000C500103E370Fd0



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