Re: [PATCH 00/33] SG table chaining support

From: Kai Makisara
Date: Mon Jul 16 2007 - 12:02:23 EST


On Mon, 16 Jul 2007, Martin K. Petersen wrote:

> >>>>> "John" == John Stoffel <john@xxxxxxxxxxx> writes:
>
> John> Will this help out tape drive performance at all? I looked
> John> through the patches quickly, esp the AIC7xxx stuff since that's
> John> what I use, but nothing jumped out at me...
>
> Yes. Most modern tape drives want a block size of 1MB or higher.
> With the old stack we'd be stuck at 512KB because the sg limitations
> caused us to come just short of 1MB...
>
Tape block sizes up to 16 MB have been possible for a very long time but
this has required tuning of the block/scsi parameters. Very few people
seem to have done this and the common (mis)belief seems to be that the
tape block size limit has been 512 kB. It is good if this tuning is not
needed in future.

--
Kai
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