SUMMARY :
I attach a new disk device to an existing mirror set.
zpool iostat poolname 5 does not report write bandwidth data
zpool iostat -v poolname 5 reports read and write data.
also seen, sometimes the output for bandwidth is non-zero but
has no units [ B, KB, MB, etc ].
I have a mirrored pool thus :
# zpool status
pool: phobos_rpool
state: ONLINE
scrub: none requested
config:
NAME STATE READ WRITE CKSUM
phobos_rpool ONLINE 0 0 0
mirror ONLINE 0 0 0
c1t0d0s0 ONLINE 0 0 0
c1t1d0s0 ONLINE 0 0 0
I attach another device :
# zpool attach phobos_rpool c1t0d0s0 c0t2d0
# zpool status
pool: phobos_rpool
state: ONLINE
status: One or more devices is currently being resilvered. The pool will
continue to function, possibly in a degraded state.
action: Wait for the resilver to complete.
scrub: resilver in progress for 0h0m, 0.42% done, 0h35m to go
config:
NAME STATE READ WRITE CKSUM
phobos_rpool ONLINE 0 0 0
mirror ONLINE 0 0 0
c1t0d0s0 ONLINE 0 0 0
c1t1d0s0 ONLINE 0 0 0
c0t2d0 ONLINE 0 0 0
The output from zpool status seems correct :
# zpool status
pool: phobos_rpool
state: ONLINE
status: One or more devices is currently being resilvered. The pool will
continue to function, possibly in a degraded state.
action: Wait for the resilver to complete.
scrub: resilver in progress for 0h7m, 37.16% done, 0h11m to go
config:
NAME STATE READ WRITE CKSUM
phobos_rpool ONLINE 0 0 0
mirror ONLINE 0 0 0
c1t0d0s0 ONLINE 0 0 0
c1t1d0s0 ONLINE 0 0 0
c0t2d0 ONLINE 0 0 0
Also, verbose iostat data seems correct :
# zpool iostat -v phobos_rpool 5
capacity operations bandwidth
pool used avail read write read write
------------ ----- ----- ----- ----- ----- -----
phobos_rpool 16.2G 17.5G 225 35 6.56M 51.6K
mirror 16.2G 17.5G 225 35 6.56M 51.6K
c1t0d0s0 - - 68 19 4.70M 52.8K
c1t1d0s0 - - 36 21 2.34M 52.8K
c0t2d0 - - 0 294 216 14.0M
------------ ----- ----- ----- ----- ----- -----
capacity operations bandwidth
pool used avail read write read write
------------ ----- ----- ----- ----- ----- -----
phobos_rpool 16.2G 17.5G 478 58 13.6M 40.4K
mirror 16.2G 17.5G 478 58 13.6M 40.4K
c1t0d0s0 - - 144 36 8.71M 40.4K
c1t1d0s0 - - 107 40 5.35M 40.3K
c0t2d0 - - 0 317 0 13.6M
------------ ----- ----- ----- ----- ----- -----
capacity operations bandwidth
pool used avail read write read write
------------ ----- ----- ----- ----- ----- -----
phobos_rpool 16.2G 17.5G 341 69 18.9M 44.4K
mirror 16.2G 17.5G 341 69 18.9M 44.4K
c1t0d0s0 - - 151 24 13.2M 44.4K
c1t1d0s0 - - 72 29 5.99M 44.4K
c0t2d0 - - 0 237 0 18.9M
------------ ----- ----- ----- ----- ----- -----
capacity operations bandwidth
pool used avail read write read write
------------ ----- ----- ----- ----- ----- -----
phobos_rpool 16.2G 17.5G 595 85 13.1M 48.7K
mirror 16.2G 17.5G 595 85 13.1M 48.7K
c1t0d0s0 - - 215 36 11.6M 50.3K
c1t1d0s0 - - 98 52 6.26M 50.3K
c0t2d0 - - 0 383 0 13.1M
------------ ----- ----- ----- ----- ----- -----
capacity operations bandwidth
pool used avail read write read write
------------ ----- ----- ----- ----- ----- -----
phobos_rpool 16.2G 17.5G 669 126 15.8M 76.5K
mirror 16.2G 17.5G 669 126 15.8M 76.5K
c1t0d0s0 - - 194 53 10.5M 75.5K
c1t1d0s0 - - 102 68 5.34M 76.4K
c0t2d0 - - 0 368 0 15.8M
------------ ----- ----- ----- ----- ----- -----
capacity operations bandwidth
pool used avail read write read write
------------ ----- ----- ----- ----- ----- -----
phobos_rpool 16.2G 17.5G 260 41 16.5M 28.0K
mirror 16.2G 17.5G 260 41 16.5M 28.0K
c1t0d0s0 - - 161 17 12.1M 29.8K
c1t1d0s0 - - 56 29 5.16M 28.7K
c0t2d0 - - 0 222 0 16.4M
------------ ----- ----- ----- ----- ----- -----
^C#
Non-verbose iostat data shows no ( near zero ) write bandwidth :
# zpool iostat phobos_rpool 5
capacity operations bandwidth
pool used avail read write read write
------------ ----- ----- ----- ----- ----- -----
phobos_rpool 16.2G 17.5G 233 36 6.98M 51.0K
phobos_rpool 16.2G 17.5G 202 10 18.6M 12.2K
phobos_rpool 16.2G 17.5G 212 15 15.5M 14.6K
phobos_rpool 16.2G 17.5G 274 43 15.5M 36.9K
phobos_rpool 16.2G 17.5G 250 24 21.1M 22.7K
phobos_rpool 16.2G 17.5G 189 15 16.8M 14.9K
phobos_rpool 16.2G 17.5G 205 21 16.8M 18.5K
^C#
I also note that the verbose output reports often show no units for read
bandwidth on the new device :
# zpool iostat -v phobos_rpool 5
capacity operations bandwidth
pool used avail read write read write
------------ ----- ----- ----- ----- ----- -----
phobos_rpool 16.2G 17.5G 375 52 8.60M 74.7K
mirror 16.2G 17.5G 375 52 8.60M 74.7K
c1t0d0s0 - - 112 29 6.21M 75.5K
c1t1d0s0 - - 59 32 3.10M 75.5K
c0t2d0 - - 0 343 104 13.3M
------------ ----- ----- ----- ----- ----- -----
See the 104 in the last row. That may be bytes, KB, or MB. That may be
documented somewhere but I suspect it is not just bytes.
Sorry if I am being nit-picky but I thought that this data would be in the
kstat chain and the per-device data would be summed up for the non-verbose
report. It looks like the write traffic to the new device is being ignored
in the non-verbose output data.
--
Dennis Clarke
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