Can you give us some numbers?
ptime dd ......
iostat -zxnd while the dd is running, so we can see what
kind of IO rates you're getting from the drives...
Thanks
roland wrote:
Hello,
i have a very weird problem on a FSC RX300 Server machine (LSI Raid controller)
i first came across this when trying Nexenta-OS, but the problem remains with
nv_109 and nv_110.
the problem is:
Writing to a ZFS volume is ok, but read performance sucks big. (slower by a
factor of 5-10, maybe even more)
if i format the same volume/slice with ufs, i don`t see this issue.
the disks are hardware raid1 and raid5 volumes and i see the same behaviour on both.
while reading from the disks (dd if=/zfs/path/to/file of=/dev/zero) , using mpstat i
don`t see anything weird - there just isn`t "happening" anything -no large time
spent in usr/sys and no large values for wait-I/O, no excessive high interrupts or
context switching....
so, why is it slow and where does solaris spend it`s time when reading from
disk?
hints ?
maybe scheduling/timer issue ?
i don`t have a clue where to look at.....
regards
roland
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