vg00 limitation

[Richard Briggs]

is there a limitation on how big vg00 can be... like how many gigs and hw many disks can be in vg00?

[Wieslaw Krajewski]

Hi,

Limits for vg00 are the same as for other volume groups. They are determined by the following options of the vgcreate command:

-p max_pv where max_pv (max number of PVs in the volume group) is not greater than 255,
-e max_pe where max_pe (max number of PE per PV) is not greater than 65535,
-s pe_size where pe_size is the size of PE, power of 2, but not greater than 256.

Rgds.

[Richard Briggs]

the reason I ask is because I went to add a 3rd pv into my vg00 and increase the size of it...and it said something like "even though this hard drive has 18gigs, you will only be able to access 10gigs due to ....i don't remember" Anyone heard anything like that?

[James R. Ferguson · Accepted solution]

Hi Richard:

I think you are referring to the 'max-pe' parameter of 'vgcreate'. 'max-pe' specifies the maximum number of physical extents that can be allocated to *any* physical disk in a volume group. The range varies from 1 to 65,535, but the value is fixed at 'vgcreate' time to be 1016 or the larger of the largeest physical volume size durin the 'vgcreate' process. The problem is that once set, 'max-pe' (and/or 'max-pv') can't be changed. Hence, adding an 18GB physical disk to a volume group originally created with a 4GB one will "waste" over 9GB of the 18GB disk.

...JRF...

[Jordan Bean]

Yep. If vg00 was created without specifying -e and -s, then the largest disk at the time was about 10 GB with 2560 PE @ 4 MB/PE. Run `vgdisplay vg00` and tell us what are 'Max PE per PV' and 'PE Size'. I don't think these parameters can be changed.

[Richard Briggs]

Everyone's sure that the parms can't be changed?

[Patrick Wallek]

Sure you can change the Max PE per PV and other VG parameters, BUT not without recreating the VG. Once those parameters are set at the creation time of the VG, that is what they are, unless you wipe out and recreate the VG.

You have a couple of options for recreating VG00 if you really want to be able to utilize your 18GB disk drive.

Method #1) Download and install Ignite/UX - http://software.hp.com/products/IUX - Create a make_tape_recovery tape and boot from it, then modify the parameters accordingly and let it rebuild your VG00.

Method #2) See Peggy Fong's response in the following thread:
http://forums.itrc.hp.com/cm/QuestionAnswer/1,1150,0xafc36af52b04d5118fef0090279cd0f9,00.html

This will allow you to create an alternate VG00 on the 18GB disk, boot from it, then add your original 2 disks back into that VG and you'd be all set.

Personally, I'd go with the Ignite/UX solution. But that's just me.