libata retry - disable?

libata retry - disable?

[Molle Bestefich]

Does anyone know of a way to disable libata's 5-time retry when a read fails?

It has the effect of causing every failed sector read to take 6
seconds before it fails, causing raid5 rebuilds to go awfully slow. 
It's generally undesirable too, when you've got RAID on top that can
write replacement data onto the failed sectors..

Log showing a failed sector:
Apr 18 09:49:53 linux kernel: end_request: I/O error, dev sda, sector 131124407
Apr 18 09:49:55 linux kernel: ata1: no sense translation for status: 0x51
Apr 18 09:49:55 linux kernel: ata1: translated ATA stat/err 0x51/00 to
SCSI SK/ASC/ASCQ 0x3/11/04
Apr 18 09:49:55 linux kernel: ata1: status=0x51 { DriveReady
SeekComplete Error }
Apr 18 09:49:56 linux kernel: ata1: no sense translation for status: 0x51
Apr 18 09:49:56 linux kernel: ata1: translated ATA stat/err 0x51/00 to
SCSI SK/ASC/ASCQ 0x3/11/04
Apr 18 09:49:56 linux kernel: ata1: status=0x51 { DriveReady
SeekComplete Error }
Apr 18 09:49:57 linux kernel: ata1: no sense translation for status: 0x51
Apr 18 09:49:57 linux kernel: ata1: translated ATA stat/err 0x51/00 to
SCSI SK/ASC/ASCQ 0x3/11/04
Apr 18 09:49:57 linux kernel: ata1: status=0x51 { DriveReady
SeekComplete Error }
Apr 18 09:49:59 linux kernel: ata1: no sense translation for status: 0x51
Apr 18 09:49:59 linux kernel: ata1: translated ATA stat/err 0x51/00 to
SCSI SK/ASC/ASCQ 0x3/11/04
Apr 18 09:49:59 linux kernel: ata1: status=0x51 { DriveReady
SeekComplete Error }
Apr 18 09:50:00 linux kernel: ata1: no sense translation for status: 0x51
Apr 18 09:50:00 linux kernel: ata1: translated ATA stat/err 0x51/00 to
SCSI SK/ASC/ASCQ 0x3/11/04
Apr 18 09:50:00 linux kernel: ata1: status=0x51 { DriveReady
SeekComplete Error }
Apr 18 09:50:01 linux kernel: ata1: no sense translation for status: 0x51
Apr 18 09:50:01 linux kernel: ata1: translated ATA stat/err 0x51/00 to
SCSI SK/ASC/ASCQ 0x3/11/04
Apr 18 09:50:01 linux kernel: ata1: status=0x51 { DriveReady
SeekComplete Error }
Apr 18 09:50:01 linux kernel: sd 0:0:0:0: SCSI error: return code = 0x8000002
Apr 18 09:50:01 linux kernel: sda: Current: sense key: Medium Error
Apr 18 09:50:01 linux kernel:     Additional sense: Unrecovered read
error - auto reallocate failed
Apr 18 09:50:01 linux kernel: end_request: I/O error, dev sda, sector 131124415
Apr 18 09:50:02 linux kernel: raid5: read error corrected!!
Apr 18 09:50:02 linux last message repeated 112 times

Re: libata retry - disable?

[Jeff Garzik]

Molle Bestefich wrote:
> Does anyone know of a way to disable libata's 5-time retry when a read fails?
> 
> It has the effect of causing every failed sector read to take 6
> seconds before it fails, causing raid5 rebuilds to go awfully slow. 
> It's generally undesirable too, when you've got RAID on top that can
> write replacement data onto the failed sectors..

libata does not retry at all.

	Jeff

Re: libata retry - disable?

[David Greaves]

Molle Bestefich wrote:
> Does anyone know of a way to disable libata's 5-time retry when a read fails?
>
> It has the effect of causing every failed sector read to take 6
> seconds before it fails, causing raid5 rebuilds to go awfully slow. 
> It's generally undesirable too, when you've got RAID on top that can
> write replacement data onto the failed sectors..
>
> Log showing a failed sector:
> Apr 18 09:49:53 linux kernel: end_request: I/O error, dev sda, sector 131124407
> Apr 18 09:49:55 linux kernel: ata1: no sense translation for status: 0x51
> Apr 18 09:49:55 linux kernel: ata1: translated ATA stat/err 0x51/00 to
> SCSI SK/ASC/ASCQ 0x3/11/04
>   
What kernel Molle?

There were some nasties in 2.6.15 to do with FUA. Have a look for my
postings in linux-ide (my problems are still not entirely resolved).

(I got very used to mdadm --force and xfs_repair during that experience!)

David

-- 

Re: libata retry - disable?

[Molle Bestefich]

David Greaves wrote:
> Molle Bestefich wrote:
> > Does anyone know of a way to disable libata's 5-time retry when a read fails?
> >
> > It has the effect of causing every failed sector read to take 6
> > seconds before it fails, causing raid5 rebuilds to go awfully slow.
> > It's generally undesirable too, when you've got RAID on top that can
> > write replacement data onto the failed sectors..
> >
> > Log showing a failed sector:
> > Apr 18 09:49:53 linux kernel: end_request: I/O error, dev sda, sector 131124407
> > Apr 18 09:49:55 linux kernel: ata1: no sense translation for status: 0x51
> > Apr 18 09:49:55 linux kernel: ata1: translated ATA stat/err 0x51/00 to
> > SCSI SK/ASC/ASCQ 0x3/11/04
> >
> What kernel Molle?
>
> There were some nasties in 2.6.15 to do with FUA. Have a look for my
> postings in linux-ide (my problems are still not entirely resolved).

2.6.16.5.  A bit surprised to see 2.6.16.7 out already.
I think the errors are (were, md-rewrite fixed it) real enough.

> (I got very used to mdadm --force and xfs_repair during that experience!)

:-)