On Wed, 26 Mar 2008, Neelakanth Nadgir wrote:
> When you experience the pause at the application level,
> do you see an increase in writes to disk? This might the
> regular syncing of the transaction group to disk.
If I use 'zpool iostat' with a one second interval what I see is two
or three samples with no write I/O at all followed by a huge write of
100 to 312MB/second. Writes claimed to be a lower rate are split
across two sample intervale.
It seems that writes are being cached and then issued all at once.
This behavior assumes that the file may be written multiple times so a
delayed write is more efficient.
If I run a script like
then the write data rate is much more consistent (at about
66MB/second) and the program does not stall. Of course this is not
Are the 'zpool iostat' statistics accurate?
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