[dm-devel] info on enabling only one path with rdac and DS4700

Johannes Hirte hirtejs at idmt.fraunhofer.de
Wed Nov 16 13:24:50 UTC 2011


On Tuesday 15 November 2011 23:35:53 Gianluca Cecchi wrote:
> - I'm going to check tomorrow about AVT current configuration as noted
> inside one of the answers.
> BTW: on the storage array there are snmp traps configured.
> After enabling multipath and rebooting the system, I still see the
> trap below, sent by the storage (only one)... Could it be related to
> this kind of configuration option at storage side?
> 
> Here the snmp message
> Summary
> Node ID: XXXX_DS4700
> Host IP Address:
> Host ID: Out-of-Band
> Event Error Code: 4011
> Event occurred: 15-nov-2011 14.49.36
> Event Message: Logical Drive not on preferred path due to ADT/RDAC failover
> Component type: Controller
> Component location: Controller in slot B

Yes, this is because the rdac module detected the LUN in AVT mode and refused
to work with it. This will happen every time you access a ghost path without
rdac.

> - On the presented LUN I configured a PV, VG, LV and ext4 fs (not system fs)
> At reboot at host side I see messages related to duplicated PV IDs for
> the paths (sdb, sdc, sdd, sde): they comes before vg activation and
> before multipathd start...
> Is this normal, because at the first vgscan run during boot, multipath
> configuration has not been instantiated yet..?
> I have to check, but I don't remember similar messages with eh el 5.7
> in other SAN configurations, where the VG is not a system VG....

You should avoid to access the sdX directly. If you need to run lvm before
multipath is up, you can blacklist the sdX in the lvm.conf.


regards,
  Johannes




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