PATCH 1/1] : Spinning up disk is observed on standby paths until timeout, resulting in longer path restoration time.

["Rengarajan, Narayanan (STSD)" <narayanan.rengarajan@xxxxxx>]

Sorry if sent already

Hi,

  Spinning up disk is observed on standby paths until timeout, resulting in longer path restoration time in 2.6.27 kernel.

 Steps to reproduce:
 1. present a standby lun to the host
 2. do a discovery from the host (scan the scsi bus)  3. Spinning of disks is  observed in  /var/log/messages

Whenever a device goes offline and comes back, the new sd device takes longer time to get created. This is because of the spinning up of disk in sd_spinup_disk fuction as the standby paths would return device not ready with 0x04/0x0b asc/ascq.

Recommended patch :

  diff -pNaur /usr/src/linux/drivers/scsi/sd.c sd.c
--- /usr/src/linux/drivers/scsi/sd.c    2009-02-09 22:24:56.000000000 +0530
+++ sd.c        2009-02-19 16:39:16.000000000 +0530
@@ -1181,8 +1181,8 @@ sd_spinup_disk(struct scsi_disk *sdkp)
                 */
                if (sense_valid &&
                    sshdr.sense_key == NOT_READY &&
-                   sshdr.asc == 4 && sshdr.ascq == 3) {
-                       break;          /* manual intervention required */
+                   sshdr.asc == 4 && (sshdr.ascq == 3 || sshdr.ascq == 
+ 0x0b ||
sshdr.ascq == 0x0c) ) {
+                       break;  /* manual intervention required || 
+ Standby ||
Unavailable */

 signed off : narayanan.rengarajan@xxxxxx

Narayanan--
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