> I get a reasonable number of 'ordered tag forced' messages. As in
> Apr 2 11:20:34 swtf kernel: sym53c895-0-<3,0>: ordered tag
forced.
> This doesn't appear to have any adverse effect on the filesystem
...,
> it's just that I'm curious as to why it is/would happen.
Refer to comment:
/*
** Force ordered tag if necessary to avoid timeouts
** and preserve interactivity.
*/
and following block of code near line 6619 in 2.4.3'ish
drivers/scsi/sym53c8xx.c.
Looks like this particular scsi driver throws out ORDERED_TAG every
3 seconds or so...
Many scsi drivers inject intermittant ORDERED_TAG like this to keep
certain SCSI targets from starving WRITE IOs under heavy load.
Hee, I spent time as "guest" (more like prisoner) of Hitachi in Toyko many
years
ago due to a problem of this nature. They were using IBM fast+wide drives
which had a tendency to defer/starve WRITE IOs for too long under heavy
load.
Regards,
-SteveR
-
To unsubscribe from this list: send the line "unsubscribe linux-scsi" in
the body of a message to [EMAIL PROTECTED]
