RE: SCSI command order issue

[Black_David@emc.com]

> Does that mean it is safe for iSCSI and other network related 
> protocols that do not provide 
> SCSI command order control, as we assume the higher layer (or 
> Operating System) may 
> take the responsibility to control the order issue ?
> 
Yes, that is the way that SCSI is generally used.  Most code that cares
about SCSI command A completing before SCSI command B waits for A to
complete before issuing B.  Examples include databases and filesystems,
and out of order completion of concurrent SCSI operations is the expected
behavior (e.g., many disks reorder their command queues for seek and
rotational optimization, and a disk array with a cache will usually
complete operations that hit in cache before operations that miss).

Thanks,
--David
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David L. Black, Senior Technologist
EMC Corporation, 42 South St., Hopkinton, MA  01748
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black_david@emc.com         Cell: +1 (978) 394-7754
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