Hi guys,

I've been having trouble with my archival kit, in the performance department rather than data loss this time (phew!).

At the point when I took these stats where was about 250 mbit of traffic outbound on an ixgb NIC on the thing, also about 100 mbit of new stuff incoming.

As you can see, the amount of disk activity far exceeds the data being served. I've disabled prefetching:

echo zfs_prefetch_disable/W0t1 | mdb -kw

and now activity looks more reasonable, the machine seems able to cope with the load, so potentially the prefetch is a bit too aggressive.

The machine itself has 8GB of RAM and is serving lots of different large files to users, so any cache will be fairly useless.


Stats: (with prefetch ENABLED)

With prefetch off most of the bandwidth figures are single / low double digits.

# uname -a
SunOS cs0 5.11 snv_116 sun4v sparc SUNW,Sun-Fire-T200

# zpool iostat 5
               capacity     operations    bandwidth
pool         used  avail   read  write   read  write
----------  -----  -----  -----  -----  -----  -----
content0    37.2T  2.85T    237      1  29.5M  9.54K
content1    28.5T  11.5T    300     53  37.4M  5.82M
content2    19.0T  1.04T    183      0  22.9M  4.27K
content3    3.85T  11.2T    312     65  39.0M  7.57M
content4    3.85T  11.2T    338     63  42.2M  7.47M
content5    3.84T  11.2T    312     65  39.0M  7.50M
content6    19.0T  1.05T    108      0  13.5M  4.12K
content7    14.0T   991G    115      0  14.4M  3.39K
----------  -----  -----  -----  -----  -----  -----
content0    37.2T  2.85T    129      0  16.1M      0
content1    28.5T  11.5T    564     57  70.5M  6.62M
content2    19.0T  1.04T     99      0  12.5M      0
content3    3.85T  11.2T    361     79  45.1M  8.08M
content4    3.85T  11.2T    995      0   124M      0
content5    3.84T  11.2T    243     46  30.3M  2.64M
content6    19.0T  1.05T      0      0      0      0
content7    14.0T   991G    203      0  25.4M      0
----------  -----  -----  -----  -----  -----  -----
content0    37.2T  2.85T    135      0  16.9M      0
content1    28.5T  11.5T    578     57  72.3M  5.79M
content2    19.0T  1.04T     96      0  12.0M      0
content3    3.85T  11.2T    377    100  47.1M  9.01M
content4    3.85T  11.2T    980      0   122M      0
content5    3.84T  11.2T    216    106  26.9M  10.4M
content6    19.0T  1.05T      0      0      0      0
content7    14.0T   991G    200      0  25.1M      0
----------  -----  -----  -----  -----  -----  -----
content0    37.2T  2.85T    131      0  16.4M      0
content1    28.5T  11.5T    578     50  72.3M  4.82M
content2    19.0T  1.04T     99      0  12.4M      0
content3    3.85T  11.2T    377     63  47.1M  6.40M
content4    3.85T  11.2T    944      0   118M      0
content5    3.84T  11.2T    243     61  30.4M  5.97M
content6    19.0T  1.05T      0      0      0      0
content7    14.0T   991G    209      0  26.1M      0
----------  -----  -----  -----  -----  -----  -----
^C

--
Tom

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