* question on SDEV_BLOCK vs. SDEV_QUIESCE
@ 2007-09-25 7:34 Oliver Neukum
2007-09-25 7:42 ` Hannes Reinecke
0 siblings, 1 reply; 3+ messages in thread
From: Oliver Neukum @ 2007-09-25 7:34 UTC (permalink / raw)
To: linux-scsi
Hi,
what is the difference between these states? What function should
I call to block a device in order to securely flush the caches?
Regards
Oliver
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: question on SDEV_BLOCK vs. SDEV_QUIESCE
2007-09-25 7:34 question on SDEV_BLOCK vs. SDEV_QUIESCE Oliver Neukum
@ 2007-09-25 7:42 ` Hannes Reinecke
2007-09-25 7:56 ` Oliver Neukum
0 siblings, 1 reply; 3+ messages in thread
From: Hannes Reinecke @ 2007-09-25 7:42 UTC (permalink / raw)
To: Oliver Neukum; +Cc: SCSI Mailing List
Oliver Neukum wrote:
> Hi,
>
> what is the difference between these states? What function should
> I call to block a device in order to securely flush the caches?
>
SDEV_BLOCK blocks _any_ commands from the midlayer; eg. if the LLDD
is doing some internal recovery.
SDEV_QUIESCE only blocks 'normal' data commands; others (like control
commands) can still get through.
So for flushing you should use SDEV_QUIESCE.
Cheers,
Hannes
--
Dr. Hannes Reinecke zSeries & Storage
hare@suse.de +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: Markus Rex, HRB 16746 (AG Nürnberg)
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^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: question on SDEV_BLOCK vs. SDEV_QUIESCE
2007-09-25 7:42 ` Hannes Reinecke
@ 2007-09-25 7:56 ` Oliver Neukum
0 siblings, 0 replies; 3+ messages in thread
From: Oliver Neukum @ 2007-09-25 7:56 UTC (permalink / raw)
To: Hannes Reinecke; +Cc: SCSI Mailing List
Am Dienstag 25 September 2007 schrieb Hannes Reinecke:
> Oliver Neukum wrote:
> > Hi,
> >
> > what is the difference between these states? What function should
> > I call to block a device in order to securely flush the caches?
> >
> SDEV_BLOCK blocks _any_ commands from the midlayer; eg. if the LLDD
> is doing some internal recovery.
> SDEV_QUIESCE only blocks 'normal' data commands; others (like control
> commands) can still get through.
>
> So for flushing you should use SDEV_QUIESCE.
Thank you, that's very helpful.
Regards
Oliver
^ permalink raw reply [flat|nested] 3+ messages in thread
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2007-09-25 7:34 question on SDEV_BLOCK vs. SDEV_QUIESCE Oliver Neukum
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