Messages in this thread |  | | Date | Sun, 15 Jul 2001 10:44:28 -0700 | From | Jonathan Lundell <> | Subject | Re: [PATCH] 64 bit scsi read/write |
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At 3:22 AM +1200 2001-07-16, Chris Wedgwood wrote: >On Sun, Jul 15, 2001 at 08:06:39AM -0700, Jonathan Lundell wrote: > > At first glance, by the way, the only write barrier I see in the > SCSI command set is the synchronize-cache command, which completes > only after all the drive's dirty buffers are written out. Of > course, without write caching, it's not an issue. > >Is the spec you have distributable? I believe some of the early drafts >were, but the final spec isn't. > >I'd really like to check it out myself, I alwasy assumed SCSI had the >smarts for write-barriers and force-unit-access but I guess I was >wrong. > >Anyhow, I'd like to see the spec for myself if it is something I can >get hold of.
I was referring to IBM's spec, as implemented in their recent SCSI and FC drives. You can find a copy at http://www.storage.ibm.com/techsup/hddtech/prodspec/ddyf_spi.pdf
WRITE EXTENDED has a bit (FUA) that will let you force that particular write to go to disk immediately, independent of write caching, but there's no suggestion that it otherwise acts as a write barrier for cached writes.
WRITE VERIFY implies a CACHE SYNCHRONIZE, so it's a write barrier, but an expensive (because synchronous) one. -- /Jonathan Lundell. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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