Reposting since it didn't get much response initially and the issue came up again in yesterday's multipath conference call. > ______________________________________________ > From: goggin, edward > Sent: Friday, July 08, 2005 12:21 AM > To: 'dm-devel@xxxxxxxxxx' > Subject: How to avoid lots of read ios to passive paths of > active-passive storage devices? > > How sould device scanning utilities like blkid, pvscan, > vgscan, and lvscan (others?) be made to avoid issuing > a significant number of read ios to passive paths of > active-passive storage devices? > > Possibly they could be changed to use device specific > command interfaces like SCSI pass through ioctls to > read the native device paths in order to avoid sending > lots of ios down the passive paths to active-passive > storage devices? > > This way they could parse the sense key, ASC, and ASCQ > returned via the SG_IO interface, see values like > "Not Ready, Manual Intervention Required" and avoid > sending subsequent reads to the same path. > > Or should they be changed to scan the multipath devices > if they exist instead of the path specific devices? > > While this isn't an issue now, it could become one later > when/if linux hosts are configured with hundreds/thousands > of passive paths. >
