Hello Tharindu,

Wednesday, July 23, 2008, 6:35:33 AM, you wrote:

TRB> Dear Mark/All,

TRB> Our trading system is writing to local and/or array volume at 10k 
TRB> messages per second.
TRB> Each message is about 700bytes in size.

TRB> Before ZFS, we used UFS.
TRB> Even with UFS, there was evey 5 second peak due to fsflush invocation.

TRB> However each peak is about ~5ms.
TRB> Our application can not recover from such higher latency.

TRB> So we used several tuning parameters (tune_r_* and autoup) to decrease
TRB> the flush interval.
TRB> As a result peaks came down to ~1.5ms. But it is still too high for our
TRB> application.

TRB> I believe, if we could reduce ZFS sync interval down to ~1s, peaks will
TRB> be reduced to ~1ms or less.
TRB> We like <1ms peaks per second than 5ms peak per 5 second :-)

TRB> Are there any tunable, so i can reduce ZFS sync interval.
TRB> If there is no any tunable, can not I use "mdb" for the job ...?

TRB> This is not general and we are ok with increased I/O rate.
TRB> Please advice/help.

txt_time/D

btw:
     10,000 * 700 = ~7MB

What's your storage subsystem? Any, even small, raid device with write
cache should help.


-- 
Best regards,
 Robert Milkowski                            mailto:[EMAIL PROTECTED]
                                       http://milek.blogspot.com

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