using LVM PV links with Informix on HP-UX
on our HP K460 i am using LVM to manage the LUN that our Informix implementation has all its raw space located. there are 4 device file paths to this LUN, 2 becuase there are 2 host bus adapters, and 2 becuase there are two RAID controllers. i will call these paths A,B,C, and D. PROBLEM: currently we are only using A, but for failover i added B as a PV link. Informix did not complain after the reboot. BUT when i decided to make B the primary path and A the alternate path, then Informix would not initialize after reboot. It could not find the last checkpoint in the root dbspace. QUESTION: does Informix support PV links? that is, if the primary path A to the LUN fails becuase of a hardware failure of a host bus adapter, then will Informix be "happy" when LVM sends I/O thru the failover path B??? NOTE: Informix was built using the LV device file names not the LUN device file names. I am assuming that using LV device file names are like using soft links to actual LUN device file names, because of LVM's ability to manage disks within a VG Sent via Deja.com http://www.deja.com/ Before you buy.
It has been some time since I worked with Informix on HP-UX but I'll see if I can remember enough to help. BTW - are you trying to create fault tolerance? Are you using MirrorUX? Try this :- 1) Don't use PV device files for anything to do with the database. As I remember, physical volumes are only "pre-prepared storage" for allocation by HP LVM. 2) If you want a "failover device" for a database chunk, create an equally sized Logical Volume to do the job (on another Physical Volume of course, or you defeat the purpose). Use symbolic links to point to the raw device for the logical volumes :- say /dev/vg00/rlvol1 is used for your rootdbs ln -s /dblinks/rootdbs /dev/vg00/rlvol1 if /dev/vg01/rlvol2 is to be your (equally sized) backup device, then ... rm /dblinks/rootdbs ln -s /dblinks/rootdbs /dev/vg01/rlvol2 ... will give you a new device for the rootdbs (provided ROOTPATH is pointing to the symlink). Of course, you would then need to do a cold restore ... BTW - try MirrorUX if you are not using it. It is very good. Hope this helps, Brett Randall yixes@my-deja.com wrote: > on our HP K460 i am using LVM to manage the LUN > that our Informix implementation has all its > raw space located. there are 4 device file paths > to this LUN, 2 becuase there are 2 host bus > adapters, and 2 becuase there are two RAID > controllers. i will call these paths A,B,C, and D. > > PROBLEM: currently we are only using A, but for > failover i added B as a PV link. Informix did not > complain after the reboot. BUT when i decided to > make B the primary path and A the alternate path, > then Informix would not initialize after reboot. > It could not find the last checkpoint in the root > dbspace. > > QUESTION: does Informix support PV links? that is, > if the primary path A to the LUN fails becuase of > a hardware failure of a host bus adapter, then > will Informix be "happy" when LVM sends I/O thru > the failover path B??? > > NOTE: Informix was built using the LV device > file names not the LUN device file names. I am > assuming that using LV device file names are like > using soft links to actual LUN device file names, > because of LVM's ability to manage disks within a > VG > > Sent via Deja.com http://www.deja.com/ > Before you buy.