autopath question

[Patricio Besteiro]

Hi All,

IOne quetion regarding autopath, should I use the first listed device on "autopath display" to use loadbalancing? or any of the device files will be ok?

for ex:

Virtual Device File : /hpap/dsk/hpap40
Load Balancing Policy : Shortest Queue Length
Lun Timeout : Infinite Retry (-1)
==================================================================
Device Path Status
==================================================================
/dev/dsk/c27t6d3 Active
/dev/dsk/c8t6d3 Active
/dev/dsk/c12t6d3 Active

I see in another thread that I should use the first path as primary because it has the same minor/mayor:

ll /hpap/dsk/hpap40
brw-r-----   1 root       sys         31 0x1b6300 Oct 15 21:12 /hpap/dsk/hpap40
ll /dev/dsk/c27t6d3
brw-r-----   1 bin        sys         31 0x1b6300 Oct  2  2008 /dev/dsk/c27t6d3

thanks in advance,

[Patrick Wallek]

Use the autopath file.

If you use the /dev/dsk/c* files, you will likely NOT see any real benefit.

[Patricio Besteiro]

Thanks Patrick for your quick response, are you suggesting to use: /hpap/dsk/* for loadbalancing? is that possible? I tought all /dev/dsk/* links should be added to the VG even using autopath.

regards,

[Duncan Edmonstone · Accepted solution]

Having used AutoPath (which was renamed as "Secure Path for Active-Active Disk Arrays") in the past, I'm going to respectfully disagree with Patrick on this one.

Once AutoPath is installed and configured, you can use any of the normal device special files under /dev/dsk in your LVM configurations - AutoPath will auto-magically make sure that the MPIO is done done all relevant paths. WHat I always used to do was add in the alternate paths to the disks anyway (like you do when configuring LVM PVlinks), just so its clear to other admins that those paths are "in use".

Although this isn't really explicitly stated in the manual, there are some examples right at the end of the latest release notes which show LVM commands using the normal DSFs:

http://bizsupport1.austin.hp.com/bc/docs/support/SupportManual/c00248508/c00248508.pdf