I have an application I have been using to manage data replication for a number of years. Recently we started using a new machine as a staging server (not that new, an x4540) running Solaris 11 with a single pool built from 7x6 drive raidz. No dedup and no reported errors.

On that box and nowhere else is see empty snapshots taking 17 or 18 seconds to write. Everywhere else they return in under a second.


Using truss and the last published source code, it looks like the pause is between a printf and the call to zfs_ioctl and there aren't any other functions calls between them:

100.5124     0.0004    open("/dev/zfs", O_RDWR|O_EXCL)            = 10
100.7582     0.0001    read(7, "\0\0\0\0\0\0\0\0ACCBBAF5".., 312)    = 312
100.7586     0.0000    read(7, 0x080464F8, 0)                = 0
100.7591     0.0000    time()                        = 1336628656
100.7653     0.0035    ioctl(8, ZFS_IOC_OBJSET_STATS, 0x08040CF0)    = 0
100.7699     0.0022    ioctl(8, ZFS_IOC_OBJSET_STATS, 0x08040900)    = 0
100.7740     0.0016    ioctl(8, ZFS_IOC_OBJSET_STATS, 0x08040580)    = 0
100.7787     0.0026    ioctl(8, ZFS_IOC_OBJSET_STATS, 0x080405B0)    = 0
100.7794     0.0001    write(1, " r e c e i v i n g   i n".., 75)    = 75
118.3551     0.6927    ioctl(8, ZFS_IOC_RECV, 0x08042570)        = 0
118.3596     0.0010    ioctl(8, ZFS_IOC_OBJSET_STATS, 0x08040900)    = 0
118.3598     0.0000    time()                        = 1336628673
118.3600     0.0000    write(1, " r e c e i v e d   3 1 2".., 45)    = 45

zpool iostat (1 second interval) for the period is:

tank        12.5T  6.58T    175      0   271K      0
tank        12.5T  6.58T    176      0   299K      0
tank        12.5T  6.58T    189      0   259K      0
tank        12.5T  6.58T    156      0   231K      0
tank        12.5T  6.58T    170      0   243K      0
tank        12.5T  6.58T    252      0   295K      0
tank        12.5T  6.58T    179      0   200K      0
tank        12.5T  6.58T    214      0   258K      0
tank        12.5T  6.58T    165      0   210K      0
tank        12.5T  6.58T    154      0   178K      0
tank        12.5T  6.58T    186      0   221K      0
tank        12.5T  6.58T    184      0   215K      0
tank        12.5T  6.58T    218      0   248K      0
tank        12.5T  6.58T    175      0   228K      0
tank        12.5T  6.58T    146      0   194K      0
tank        12.5T  6.58T     99    258   209K  1.50M
tank        12.5T  6.58T    196    296   294K  1.31M
tank        12.5T  6.58T    188    130   229K   776K

Can anyone offer any insight or further debugging tips?

Thanks.

--
Ian.

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