From: Jeff Garzik <jgarzik@pobox.com>
To: Tony Battersby <tonyb@cybernetics.com>
Cc: linux-ide@vger.kernel.org
Subject: Re: [PATCH] libata: increase 128 KB / cmd limit for ATAPI tape drives
Date: Sat, 03 Nov 2007 08:48:42 -0400 [thread overview]
Message-ID: <472C6E2A.8020809@pobox.com> (raw)
In-Reply-To: <47275163.9020809@cybernetics.com>
Tony Battersby wrote:
> Commands sent to ATAPI tape drives via the SCSI generic (sg) driver are
> limited in the amount of data that they can transfer by the max_sectors
> value. The max_sectors value is currently calculated according to the
> command set for disk drives, which doesn't apply to tape drives. The
> default max_sectors value of 256 limits ATAPI tape drive commands to
> 128 KB. This patch against 2.6.24-rc1 increases the max_sectors value
> for tape drives to 65535, which permits tape drive commands to transfer
> just under 32 MB.
>
> Tested with a SuperMicro PDSME motherboard, AHCI, and a Sony SDX-570V
> SATA tape drive.
>
> Note that some of the chipset drivers also set their own max_sectors
> value, which may override the value set in libata-core. I don't have
> any of these chipsets to test, so I didn't go messing with them. Also,
> ATAPI devices other than tape drives may benefit from similar changes,
> but I have only tape drives and disk drives to test.
>
> Signed-off-by: Tony Battersby <tonyb@cybernetics.com>
applied
prev parent reply other threads:[~2007-11-03 12:48 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-10-30 15:44 [PATCH] libata: increase 128 KB / cmd limit for ATAPI tape drives Tony Battersby
2007-10-31 12:50 ` Alan Cox
2007-11-03 12:48 ` Jeff Garzik [this message]
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