From: jshankar <jshankar@CS.ColoState.EDU>
To: James Bottomley <James.Bottomley@SteelEye.com>
Cc: linux-scsi <linux-scsi@vger.kernel.org>
Subject: RE: queue depth help!!
Date: Wed, 31 Dec 2003 09:23:27 -0700 [thread overview]
Message-ID: <3FF4A594@webmail.colostate.edu> (raw)
Hello James,
Case :queue depth=1
On issuing a scsi command write, does the data needs to be written
succesfully
to disk before issuing a scsi response. Is there a chance that the previous
command's data is still cached on scsi controller and the next command issued
is executed.
Please let me know if there are any good tools for scsi analyzer.
Thanks
Jay
>===== Original Message From James Bottomley <James.Bottomley@SteelEye.com>
=====
>On Sat, 2003-12-27 at 15:38, jshankar wrote:
>> if the scsi target queue depth is 1, does it mean that i can handle only
one
>> outstanding command at a time.
>
>Yes
>
>> Does it mean if another command is issued( queue depth=1), it has to wait
till
>> the previous command is done.
>
>Yes.
>
>The mid-layer will start the queued command as soon as the one occupying
>the device returns...this is often why untagged devices actually set
>their depth to 2 so they can have another command all prepared and ready
>to roll as soon as the in-progress one returns.
>
>James
next reply other threads:[~2003-12-31 16:23 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-12-31 16:23 jshankar [this message]
2003-12-31 16:26 ` queue depth help!! James Bottomley
-- strict thread matches above, loose matches on Subject: below --
2003-12-27 21:38 jshankar
2003-12-27 21:46 ` James Bottomley
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