Hello, I was doing performance testing, validating zvol performance in particularly, and found that zvol write performance to be slow ~35-44MB/s at 1MB blocksize writes. I then tested the underlying zfs file system with the same test and got 121MB/s. Is there any way to fix this? I really would like to have compatible performance between the zfs filesystem and the zfs zvols.
# first test is a file test at the root of the zpool vg_satabeast8_vol0 dd if=/dev/zero of=/vg_satabeast8_vol0/testing bs=1M count=32768 32768+0 records in 32768+0 records out 34359738368 bytes (34 GB) copied, 285.037 s, 121 MB/s # create zvol zfs create -V 100G -b 4k vg_satabeast8_vol0/lv_test # test zvol with 'dsk' device > dd if=/dev/zero of=/dev/zvol/dsk/vg_satabeast8_vol0/lv_test bs=1M count=32768 32768+0 records in 32768+0 records out 34359738368 bytes (34 GB) copied, 981.219 s, 35.0 MB/s # test zvol with 'rdsk' device (results are better than 'dsk', however, not as good as a regular file) dd if=/dev/zero of=/dev/zvol/rdsk/vg_satabeast8_vol0/lv_test bs=1M count=32768 32768+0 records in 32768+0 records out 34359738368 bytes (34 GB) copied, 766.247 s, 44.8 MB/s >uname -a SunOS zfs-debug-node 5.11 snv_130 i86pc i386 i86pc Solaris I believe this problem is affecting performance tests others are doing with Comstar and exported zvol logical units. Steffen _______________________________________________________________________________________________ Steffen Plotner Amherst College Tel (413) 542-2348 Systems/Network Administrator/Programmer PO BOX 5000 Fax (413) 542-2626 Systems & Networking Amherst, MA 01002-5000 swplot...@amherst.edu
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