On 01/03/2012 08:20 PM, Rob Evers wrote:
> From: Rob Evers <revers@xxxxxxxxxx>
>
> When alua targets are transitioning, the scsi midlayer retry mechanism
> continuously retries the scsi commands that are returning with not ready
> transitioning status. The target is not capable of handling the
> commands for time on the order of several seconds during these transistions.
>
> This patch delays the device queue for 2 seconds, which is in the same
> order of aas transition time.
>
> Also, handle all other cases where ADD_TO_MLQUEUE_DELAY could be returned
> instead of ADD_TO_MLQUEUE as if ADD_TO_MLQUEUE were being returned.
>
> Problem found by array partner testing
>
> change MLQUEUE_DEV_DLY_RTY to MLQUEUE_DELAYED_RETRY
>
I have been working on a different solution, whic
> Signed-off-by: Rob Evers <revers@xxxxxxxxxx>
> ---
> drivers/scsi/device_handler/scsi_dh_alua.c | 7 ++++---
> drivers/scsi/scsi.c | 3 +++
> drivers/scsi/scsi_error.c | 1 +
> drivers/scsi/scsi_lib.c | 9 ++++++++-
> include/scsi/scsi.h | 12 +++++++-----
> 5 files changed, 23 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c b/drivers/scsi/device_handler/scsi_dh_alua.c
> index 4ef0212..33b8df7 100644
> --- a/drivers/scsi/device_handler/scsi_dh_alua.c
> +++ b/drivers/scsi/device_handler/scsi_dh_alua.c
> @@ -233,7 +233,7 @@ static void stpg_endio(struct request *req, int error)
> goto done;
> }
> err = alua_check_sense(h->sdev, &sense_hdr);
> - if (err == ADD_TO_MLQUEUE) {
> + if (err == ADD_TO_MLQUEUE || err == ADD_TO_MLQUEUE_DELAY) {
> err = SCSI_DH_RETRY;
> goto done;
> }
> @@ -443,7 +443,7 @@ static int alua_check_sense(struct scsi_device *sdev,
> /*
> * LUN Not Accessible - ALUA state transition
> */
> - return ADD_TO_MLQUEUE;
> + return ADD_TO_MLQUEUE_DELAY;
> if (sense_hdr->asc == 0x04 && sense_hdr->ascq == 0x0b)
> /*
> * LUN Not Accessible -- Target port in standby state
> @@ -521,7 +521,8 @@ static int alua_rtpg(struct scsi_device *sdev, struct alua_dh_data *h)
> return SCSI_DH_IO;
>
> err = alua_check_sense(sdev, &sense_hdr);
> - if (err == ADD_TO_MLQUEUE && time_before(jiffies, expiry))
> + if ((err == ADD_TO_MLQUEUE || err == ADD_TO_MLQUEUE_DELAY) &&
> + time_before(jiffies, expiry))
> goto retry;
> sdev_printk(KERN_INFO, sdev,
> "%s: rtpg sense code %02x/%02x/%02x\n",
Actually, this doesn't help if the RTPG command returns with the
mentioned error; then you'll just continue flooding the array with
RTPG commands. You'll need to delay the RTPG commands, too.
I'll be sending an updated patch.
Cheers,
Hannes
--
Dr. Hannes Reinecke zSeries & Storage
hare@xxxxxxx +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: J. Hawn, J. Guild, F. Imendörffer, HRB 16746 (AG Nürnberg)
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