Autoswitch on disks

[JOHN TURNER_2]

it has been pointed out that when you do a vgdisplay -v on one of my machines there appears to be no autoswitch in the disk information and on another machine of the same spec, the autoswitch is visible, what do i need to do to set up or enable auto switch

machine1
PV Name
PV Status
Total PE
Free PE

machine2
PV name
PV status
Total PE
Free PE
Autoswitch

[Stefan Farrelly]

This is indeed very strange. Does it affect every physical volume on the machine1 (pvdisplay for each pv has no autoswitch) ?

All I can think is that it is a patch issue, I know of nothing else which can turn off this option or remove it from a vgdisplay -v or pvdispaly. Check the patch levels (LVM patches) between machine1 and 2.

[James Murtagh]

Hi John,

I'd imagine one volume group has alternate links to the disk devices and one doesn't. The autoswitch flag is only relevant if one link fails and lvm can switch to the other. You should be able to tell from the PV counts in vgdisplay and also from the disk descriptions in the PV section at the tail of the output when using the -v flag.

Cheers,

James.

[Robert-Jan Goossens]

Hi,

I think Stefan is right, take a look at next doc.

Document description: vgdisplay and pvdisplay now show "autoswitch" parameter
Document id: KBRC00005073


http://www4.itrc.hp.com/service/cki/docDisplay.do?docLocale=en_US&docId=200000062907289

Robert-Jan.

[James R. Ferguson · Accepted solution]

Hi John:

If this is 11.0 make sure that the server that doesn't show the 'autoswith' option has patch PHCO_20870 installed. This patch is superseded by PHCO_23791 or PHCO_24437.

Regards!

...JRF...

[RolandH]

Hi John,

the Autoswitch parameter is for alternate path option. So if there are two path to one disk and autoswitch is set to on the system will switch to the other path if one exist.
To see if one exist do a vgdisplay -v.
You will see devices, which a tagged with "alternate link" at the PV Name line.

And here is the differance to your system. I think you have no alternate path configuration.
But on systems with the newest LVM patches installed the parameter Autoswitch is showed anyhow.


HTH
Roland

PS: On your system where Autoswitch is showed, see the man page from vgdisplay.