Good document on emc powerlink site about setting up gfs6.1 and powerpath. https://powerlink.emc.com/nsepn/webapps/btg548664833igtcuup4826/km/live1/en_ US/Offering_Technical/Technical_Documentation/300-003-820_a01_elccnt_0.pdf?m tcs=ZXZlbnRUeXBlPUttQ2xpY2tTZWFyY2hSZXN1bHRzRXZlbnQsZG9jdW1lbnRJZD0wOTAxNDA2 NjgwMTg3YjFhLGRhdGFTb3VyY2U9RENUTV9lbl9VU18w Page 18 I believe has the filtering solution you are after for point 2. Ben > -----Original Message----- > From: linux-cluster-bounces@xxxxxxxxxx > [mailto:linux-cluster-bounces@xxxxxxxxxx] On Behalf Of Celso K. Webber > Sent: 23 September 2006 04:08 > To: linux clustering > Subject: LVM and Multipath with EMC PowerPath > (Was: CLVMD -Do I need it) > > 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, because the > first server that "sees" the PVs will initialize them, and > the other server will see the LVM objects as inactive. This > is solved in LVM2 when used together with CLVM, right? I'm > not pretty sure about the mecanics of CLVM, but I imagine it > shares device UUIDs between the machines. So far, so good. > > 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: > [root@csumccaixa12 network-scripts]# pvscan > Found duplicate PV 7v9XUzPHIRqe6E0fA6hgCR3ybeaJoiWm: using > /dev/sdc1 not /dev/emcpowerb1 > Found duplicate PV 3eKnMIm00kg6DXn4MW1UX9QCFh96ykwG: using > /dev/emcpowerc1 not /dev/sdb1 > Found duplicate PV 3T00PR5Ky1XrBesYHRtyowoBQLWDO1kd: using > /dev/sdd1 not /dev/emcpowera1 > Found duplicate PV 3eKnMIm00kg6DXn4MW1UX9QCFh96ykwG: using > /dev/sde1 not /dev/emcpowerc1 > Found duplicate PV 7v9XUzPHIRqe6E0fA6hgCR3ybeaJoiWm: using > /dev/sdf1 not /dev/sdc1 > Found duplicate PV 3T00PR5Ky1XrBesYHRtyowoBQLWDO1kd: using > /dev/sdg1 not /dev/sdd1 > PV /dev/sda3 VG vg0 lvm2 [59.81 GB / 37.75 GB free] > PV /dev/sdg1 lvm2 [127.43 GB] > PV /dev/sde1 lvm2 [127.43 GB] > PV /dev/sdf1 lvm2 [127.43 GB] > Total: 4 [442.10 GB] / in use: 1 [59.81 GB] / in no VG: 3 > [382.29 GB] > > You can see above that the /dev/emcpowerX devices were > declined in favor of the real Linux devices. "vg0" is a VG in > the internal disks (/dev/sda). > > The problem I see here is that whenever the specific device > that LVM2 chose goes down because of a link failure, LVM will > not automatically failover to another device, will it? In my > tests it didn't. > > 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. > > > Question 1: did anyone solve this problem? Does > device-mapper-multipath solve this problem? > > Question 2: is there a way to "force" which devices LVM > should employ when scanning the PVs over the disks Linux recognize? > > > Thank you all for any hints on this. > > Regards, > > Celso. > -- > *Celso Kopp Webber* > > celso@xxxxxxxxxxxxxxxx <mailto:celso@xxxxxxxxxxxxxxxx> > > *Webbertek - Opensource Knowledge* > (41) 8813-1919 > (41) 3284-3035 > > > -- > Esta mensagem foi verificada pelo sistema de antivírus e > acredita-se estar livre de perigo. > > -- > Linux-cluster mailing list > Linux-cluster@xxxxxxxxxx > https://www.redhat.com/mailman/listinfo/linux-cluster > > -- Linux-cluster mailing list Linux-cluster@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/linux-cluster
