[Linux-cluster] LVM and Multipath with EMC PowerPath (Was: CLVMD - Do I need it)
Roger Peña Escobio
orkcu at yahoo.com
Sat Sep 23 21:16:13 UTC 2006
--- "Celso K. Webber" <celso at webbertek.com.br> wrote:
> Hello all,
>
> After reading a thread on this list (CLVMD - Do I
> need it), I started
> playing around with CLVM, just to make sure two
> problems I had in the
> past were solved:
>
> 1) LVM normally cannot be used on shared disks,
[...]
> 2) The other problem is not directly related to
> CLVM, but I found no
> solution for it (yet). In my setup, I have multiple
> paths to the same
> devices in the shared storage (either in a SAN or
> DAS). Under the EMC
> solution, we employ PowerPath to solve the multiple
> devices issue for
> each LUN. It works quite well. But LVM is not aware
> of PowerPath's
> multiple path aggregation, so when it scans the PVs
> on the LUN's
> partitions, it "finds" duplicates for the PVs, like
> this:
tyhe solution for this is to "filter" the
"under-powerpath devices" :-)
I mean, to filter to not scan the devices exported by
the SAN or DAS, and just use the powerpath devices for
the LVM
check the file /etc/lvm/lvm.conf
> Another matter is that using the /dev/emcpowerX
> devices I have also load
> balancing, so even if LVM2 did failover to the other
> paths (the other
> devices), I would loose the load balancing feature I
> can achieve with
> PowerPath.
if you put LVM over powerpath, you are layering the
environment, do you?
path load balancing and failover are cover by
powerpath, and LVM do its own business :-)
> Question 2: is there a way to "force" which devices
> LVM should employ
> when scanning the PVs over the disks Linux
> recognize?
/etc/lvm/lvm.conf
# A filter that tells LVM2 to only use a restricted
set of devices.
# The filter consists of an array of regular
expressions. These
# expressions can be delimited by a character of your
choice, and
# prefixed with either an 'a' (for accept) or 'r' (for
reject).
# The first expression found to match a device name
determines if
# the device will be accepted or rejected (ignored).
Devices that
# don't match any patterns are accepted.
cu
roger
__________________________________________
RedHat Certified Engineer ( RHCE )
Cisco Certified Network Associate ( CCNA )
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