Messages in this thread | | | Subject | Re: safe file systems | Date | Wed, 24 Sep 1997 22:36:36 -0500 | From | Doug Ledford <> |
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-------- > > Also, your writes have to be very strictly ordered. Some intelligent IO > > subsystems will reorder your write operations on you, which I guess could > > cause lots of really obscure hard to track down funnies if you were unaware > > of you IO doing this. > > SCSI itself has flags to stop that happening. We don't appear to have any way > right now to mark a request ordered let alone tell the scsi layer to tell > the card to order it.
IDE doesn't have this problem as long as there is no write cacheing enabled on the drive itseslf. SCSI can get around the problem by disabling tagged queueing (as an immediate fix), or by adding an ordered tag flag for commands on tagged queueing devices. However, to truly gaurantee ordered writes on SCSI you would have to disable drive write cacheing here as well.
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