Douglas Gilbert wrote: > Arjan van de Ven wrote: >> On Tue, 2006-07-25 at 16:28 -0600, Moore, Eric wrote: >>> -- Tuesday, July 25, 2006 4:22 PM, Michael Reed wrote: >>>> Using fibre channel disks, I've noticed that when the system shuts down >>>> that the sd_driver issues a sync cache command to the device. I've >>>> also >>>> noticed that when the lldd is removed via rmmod that this sync cache is >>>> not executed. I would think that the sync cache would be desirable >>>> under this circumstance. >>>> >>> This is not handled from sg path as well. Meaning if you >>> use sdparm, and enable the caching page WCE bit, then reboot, >>> there is no SYNC cache issued from above. >>> We handle this in fusion drivers due to short coming from above. >> >> >> Hi, >> >> that sounds sooo like the wrong approach... wouldn't it be better to fix >> sg instead? > > Uh? sg is just a pass through. As such it can subvert > policy decisions of the kernel. That isn't always a > bad thing :-) > > The design flaw is any driver that tries to maintain a > state variable associated with a device (logical unit) > and can't cope with situations when it gets out of sync. > If you managed to neuter the pass through, how would you > cope with another initiator? Perhaps the best policy for sd is to assume that WCE is enabled and just issue the sync cache. -- I'm wondering about the policy of issuing a sync cache. There are target removal paths which result in it not being issued. So, the real question is: when a scsi target is removed, is it policy that sync cache will be issued? In fibre channel, here are two code paths in which sync cache is not issued. - removal of LLDD (rmmod) - removal of target via sysfs device/delete In a closer look at the target removal via sysfs device/delete, I observe that portions of the sysfs fc_remote_ports/rport-* remain in place. Do we need to tie the device/delete to the transport? Can of worms? Close eyes, run screaming? Mike > > Doug Gilbert > - > : send the line "unsubscribe linux-scsi" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > > - : send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
