[dm-devel] Multipath and getuid_callout issues withHPXP1024disk array

[malahal at us.ibm.com]

Greene, Rick [rick.greene at ncogroup.com] wrote:
> create: mpath0 (05:83)
> [size=13 GB][features="0"][hwhandler="0"]
> \_ round-robin 0
>  \_ 1:0:0:0 sda 8:0   [ready]
> \_ round-robin 0
>  \_ 2:0:0:0 sde 8:64  [ready]

The above out displays two states for me. Maybe your version only
displays one.

> 1) does the actual WWID need to be in the "uid" value that multipath
> gets from the callout, or is any value that is unique to the disk good
> enough?
 
I think, it can be anything. Doesn't need to match actual WWID.

> 2) what is the character limit to the return value from the
> getuid_callout?

Old versions had it as 64 (63 actual chars) and the latest code has it
set to 128 (maybe 127 real chars)

> 3) is there a specific format that multipath is looking at for parsing
> the info in the uid value (such as vendor, model, type, serial number,
> etc), or is the unique disk identifier all that is needed?

As far as I know, it doesn't parse anything inside WWID. Make sure you
don't have any blanks in the WWID as the bindings file parser will have
trouble if you do have.