Mirroring and recovering LVM volumes
We are working on trying out some new HA and/or recovery techniques with SLES 11 SP3 and our new SVC hardware. One thing that I would like to try is setting up mirroring via the SVC of a LUN that has mysql data on it. This LUN is dedicated to a SLES 11 SP3 server on our z114, but it is also part of a logical volume. (Right now, its a 1 physical volume LVM.) Setting up the mirroring is not a problem. My question is more related to recovery. I don't know a lot about how LVM works. How much about the volume is stored on the LUN itself and how much is stored elsewhere in the opsys filesystem? If we have a recovery server pointed to the mirrored volume, will it see the LVM metadata? Any hints/tips on mirroring LVM volumes? Or, should we stay away from LVM for anything we want to mirror? Martha -- For LINUX-390 subscribe / signoff / archive access instructions, send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390 -- For more information on Linux on System z, visit http://wiki.linuxvm.org/
Re: Mirroring and recovering LVM volumes
I recommend that you follow the UUIDs and let LVM do the hard part for you. Each PV in a VG has a unique unit ID. In practice, they truly are unique. Think of it like a label, but better. The logical volume manager finds what meta-data it needs on each PV to know what VG it belongs to and what other PVs are required. So ... you might want to invetory LUNs by UUID and group them by VG. Primary LUN will have one or more physical identifiers. (ie: WWPN of each FA and the LUN number assigned) It will also have its LVM-space UUID. The secondary LUN will have different physical identifiers. (assigned LUN number may be the same, but FA WWPNs will surely be different) But the UUID should match. (It's a copy, after all.) And hopefully you don't also have partitioning in the way. But if you do, it should not hurt your inventory scheme. On Tue, Dec 17, 2013 at 10:55 AM, Martha McConaghy u...@vm.marist.edu wrote: We are working on trying out some new HA and/or recovery techniques with SLES 11 SP3 and our new SVC hardware. One thing that I would like to try is setting up mirroring via the SVC of a LUN that has mysql data on it. This LUN is dedicated to a SLES 11 SP3 server on our z114, but it is also part of a logical volume. (Right now, its a 1 physical volume LVM.) Setting up the mirroring is not a problem. My question is more related to recovery. I don't know a lot about how LVM works. How much about the volume is stored on the LUN itself and how much is stored elsewhere in the opsys filesystem? If we have a recovery server pointed to the mirrored volume, will it see the LVM metadata? Any hints/tips on mirroring LVM volumes? Or, should we stay away from LVM for anything we want to mirror? Martha -- For LINUX-390 subscribe / signoff / archive access instructions, send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390 -- For more information on Linux on System z, visit http://wiki.linuxvm.org/ -- -- R; Rick Troth Velocity Software http://www.velocitysoftware.com/ -- For LINUX-390 subscribe / signoff / archive access instructions, send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390 -- For more information on Linux on System z, visit http://wiki.linuxvm.org/
Re: Mirroring and recovering LVM volumes
On 12/17/2013 at 10:55 AM, Martha McConaghy u...@vm.marist.edu wrote: Setting up the mirroring is not a problem. My question is more related to recovery. I don't know a lot about how LVM works. How much about the volume is stored on the LUN itself and how much is stored elsewhere in the opsys filesystem? All of the metadata needed to reconstruct the VG is on the physical disk itself. The only time you need anything from /etc/lvm/ is when any of that gets damaged and needs to be rewritten. If we have a recovery server pointed to the mirrored volume, will it see the LVM metadata? It should, yes. Any hints/tips on mirroring LVM volumes? Or, should we stay away from LVM for anything we want to mirror? You can also use LVM itself to mirror the data. See man lvcreate for the -m/--mirrors option. Either way, I don't see any reason why you shouldn't use the SVC itself to mirror the disk(s). Mark Post -- For LINUX-390 subscribe / signoff / archive access instructions, send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390 -- For more information on Linux on System z, visit http://wiki.linuxvm.org/
Re: Mirroring and recovering LVM volumes
You can also use LVM itself to mirror the data. See man lvcreate for the - m/--mirrors option. Either way, I don't see any reason why you shouldn't use the SVC itself to mirror the disk(s). I'd second this approach. One less thing to deal with in software configuration management. -- For LINUX-390 subscribe / signoff / archive access instructions, send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390 -- For more information on Linux on System z, visit http://wiki.linuxvm.org/
Weird
Playing Words with Friends, it accepts bash and sh as words, but not ksh. What's up with that? J .phsiii -- For LINUX-390 subscribe / signoff / archive access instructions, send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390 -- For more information on Linux on System z, visit http://wiki.linuxvm.org/
Re: Weird
'Cause the Korn Shell Sucks! Playing Words with Friends, it accepts bash and sh as words, but not ksh. What's up with that? J -- For LINUX-390 subscribe / signoff / archive access instructions, send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390 -- For more information on Linux on System z, visit http://wiki.linuxvm.org/
