I'm seeing some strange behavior from OCFS2 while trying to mount mpath/dm-multipath devices under RHEL5. Sometimes I can mount the EMC-connected, dual-pathed volumes just fine and sometimes I get "device busy" errors. I've tried mounting by label and also by explicit /dev/mapper/mpathXpY name with the same unpredictable behavior. I've also noticed that sometimes when a device is successfully mounted on all nodes, each node may return different output from the mount command regarding the device mounted; e.g. /dev/mapper/mpath0p1 vs. /dev/dm-17. One consistent aspect I have noticed whenever I receive the "device busy" error is that the /dev/dm-X names don't match up on each node. I also see that ocfs2console refers to each device by the /dev/dm-X name instead of the /dev/mapper/XX name. I guess my question is simply: Are dm-multipath devices supported under OCFS2? Are multipathed devices not recommended with OCFS2? Any documentation available on this?
> -----Original Message----- > From: ocfs2-users-bounces at oss.oracle.com [mailto:ocfs2-users- > bounces at oss.oracle.com] On Behalf Of Masaryk Kevin D > Sent: 02/24/2009 13:21 > To: ocfs2-users at oss.oracle.com > Subject: [Ocfs2-users] mounting mpath devices > > I'm seeing some strange behavior from OCFS2 while trying to mount > mpath/dm-multipath devices under RHEL5. Sometimes I can mount the > EMC-connected, dual-pathed volumes just fine and sometimes I get > "device > busy" errors. I've tried mounting by label and also by explicit > /dev/mapper/mpathXpY name with the same unpredictable behavior. I've > also noticed that sometimes when a device is successfully mounted on > all > nodes, each node may return different output from the mount command > regarding the device mounted; e.g. /dev/mapper/mpath0p1 vs./dev/dm-17.> > One consistent aspect I have noticed whenever I receive the "device > busy" error is that the /dev/dm-X names don't match up on each node. I > also see that ocfs2console refers to each device by the /dev/dm-X name > instead of the /dev/mapper/XX name. > > I guess my question is simply: Are dm-multipath devices supportedunder> OCFS2? Are multipathed devices not recommended with OCFS2? Any > documentation available on this?We are using OCFS2 with device-mapper-multipath (4 paths) and we use the /dev/mapper/XX names. Names match across machines although we did not particular paid attention to make it the same. Regards, Ulf. --------------------------------------------------------------------- OPENLANE Inc., T: 650-532-6382, F: 650-532-6441 4600 Bohannon Drive, Suite 100, Menlo Park, CA 94025 ---------------------------------------------------------------------
On Tue, Feb 24, 2009 at 02:21:03PM -0700, Masaryk Kevin D wrote:> I'm seeing some strange behavior from OCFS2 while trying to mount > mpath/dm-multipath devices under RHEL5. Sometimes I can mount the > EMC-connected, dual-pathed volumes just fine and sometimes I get "device > busy" errors. I've tried mounting by label and also by explicit > /dev/mapper/mpathXpY name with the same unpredictable behavior. I've > also noticed that sometimes when a device is successfully mounted on all > nodes, each node may return different output from the mount command > regarding the device mounted; e.g. /dev/mapper/mpath0p1 vs. /dev/dm-17.I'm unsure as to why you get the 'device busy' errors. That's the weird thing. Mounting by label makes you vulnerable to the whims of blkid - whichever /dev name it finds first is what you'll see in the output of mount(8). But in the end, it should be the same device (that is, /dev/mapper/mpath0p1 is probably the same thing as /dev/dm-17).> One consistent aspect I have noticed whenever I receive the "device > busy" error is that the /dev/dm-X names don't match up on each node. I > also see that ocfs2console refers to each device by the /dev/dm-X name > instead of the /dev/mapper/XX name.The /dev/dm-X names are not intended to match up. They appear in the order the system discovers them. The multipath daemon is responsible for matching the /dev/dm-X name to the consistent /dev/mapper/mpathXpY name. So if you want to see a consistent name, use that one.> I guess my question is simply: Are dm-multipath devices supported under > OCFS2? Are multipathed devices not recommended with OCFS2? Any > documentation available on this?They should work, and they are absolutely recommended. Joel -- "If at first you don't succeed, cover all traces that you tried." -Unknown Joel Becker Principal Software Developer Oracle E-mail: joel.becker at oracle.com Phone: (650) 506-8127