[skibum]

Hi All,

We're prepping for an AIX 5.3 new install and have questions about configuring additional volume groups and logical volumes. Please don't laugh, as this is a development env so we have two pseries machines, each with 2/74GB disks. One machine will be a test app server, while the other will be a db server...each with very little user data. The thought is to use hdisk0 for rootvg, and hdisk1 for datavg....and I'm a bit confused as to how much of hdisk0 rootvg is going to use, and whether or not we can create another vg on hdisk0, or if we even should?

The documentation seems thorough enough to take us through the BOS install, but then doesn't really tell us what we have at the vg and lv level when we boot next time. So, I'll assume we'll have only rootvg and all of it's file systems on hdisk0. If so, will we be able to/should we add another vg/lv on hdisk0, or should we put the datavg and lv's on hdisk1.

It just seems like a waste of space if rootvg uses the whole boot disk.

No RAID cards were purchased for either machine :-(

Looks forward to your suggestions!

Thanks,

Steve

[ross.mather]

The Logical Volume Manager requires that a Disk is fully used for one Volume Group.

You don't need RAID cards to do mirroring, the LVM can take care of that.

Whether you are going to mirror or not depends on how much risk you are prepared to take in losing data, and whether or not the recovery time will be acceptable near your development deadlines. Always assume the worst case for a failure :-).

The OS will fit in comfortably in 20Gb, so you have 50 Gb wasted on the root disk.

If you have less that 50Gb of data in this case you can choose to put all the data on the rootvg and mirror the disks.

The only major drawback is that if you make an mksysb of the server for backup purposes.

Of course buying 2 extra disks per server (assuming you have the drive bays for them) means less headaches and less risk of data loss.

cheers
Ross

[riscy]

You may also create logical volumes in the rootvg for your data. Then backing up with mksysb you can define excludes (-e <exlcude_file>). This way only rootvg stuff will be backed up in the mksysb image. Check out the manpage of mksysb. Below some lines:

<man_snippet>
-e Excludes files listed in the /etc/exclude.rootvg file from being backed up. The rules for exclusion follow the pattern matching rules of the grep command.Note: If you want to exclude certain files from the backup, create the /etc/exclude.rootvg file, with an ASCII editor, and enter the patterns of file names that you do not want included in your system backup image. The patterns in this file are input to the pattern matching conventions of the grep command to determine which files will be excluded from the backup. If you want to exclude files listed in the /etc/exclude.rootvg file, select the Exclude Files field and press the Tab key once to change the default value to yes.

</man_snippet>

HTH, Riscy

[skibum]

great posts, guys....thanks!