Disk limitation on HP-UX 10.20?

[Jesse Dougherty]

can anyone tell me if 10.20 has a disk limitation? We are trying to install 4 x 150GB drives in a J5000 using 10.20 and the box is only seeing 45GB.


Thanks
Jesse
Cypress Tech

[TwoProc · Accepted solution]

What exactly are you doing/using when it only "sees" 45Gig? You should be able to do this, but I expect that you'd need new volume groups and you'd have to use the "-e" parameter of vgcreate to make sure you could use all of the extents, and you will probably have to use 8M extents instead of the default 4M.

Are you not seeing the rest of the space from "pvdisplay"? diskinfo? Show us what you mean by posting output.

[Patrick Wallek]

If only 45 GB is being seen from vgdisplay then you need to look at changing 'max pe per pv' and 'pe size' at a minimum when creating the VG.

[Glenn S. Davidson]

John is correct. Is the 45GB for one drive or all drives?

Before you start creating logical volumes make sure you adjust the parameters in the kernel so you don't hit another limit. I don't remember exactly but I think you are limited to something like 16 VGs and 16 lvols unless you change them.

If you added them to an existing VG then you won't see space past the number of extents that were available when you created the VG.

[whiteknight]

Jesse,

Usually, if you set up a new volume group without any command line switches, the default physical extent size (pe_size=4MB) is used. pe_size can be in the range 1 to 256MB. pe_size must be equal to a power of 2 (1, 2, 4, 8, etc.). The default value for maximal physical extents (max_pe) is 1016.

However, if the size of any physical volume exceeds 1016 times the pe_size, the default value for max_pe is adjusted automatically to match the physical volume size. The maximum number of physical extents can be a value in the range 1 to 65535.

This automatic procedure does not work, if you manually set the pe_size, e.g.:

# vgcreate -s 8 vgXY /dev/dsk/cCtTdD

In this example the vgcreate only works with disks smaller or equal than 8128 MB (1016 times 8MB).

If you want to use larger disks you have also to apply the max_pe value, e.g. for a 64GB disk:

# vgcreate -s 8 -e 8192 vgXY /dev/dsk/cCtTdD

NOTE: Plan these values carefully, thinking of the largest disk you want to use in the future. You cannot change pe_size and max_pe, resp., for an existing volume group.

Hope this help
WK
please assign points

[Andrew Rutter]

jesse,

hpux 10.20 does have limitations yes.

I came across this a while ago, while even trying 36gb disks.

however, with abit of testing came up with this conclusion. Like you probably cannot, i couldnt find any info on the exact limitations. root disks are different than data disks, and have only tried it on the root vg. But to get round it we need to increase the max pe and the size of the pe.

the max pe is very limitedin 10.20, not like 11.x.

I also did abit of testing today aswell, as ive been doing a 10.20 install, using the dec 99 media. Roughly the max_pe value cannot exceed much more than 5600. This times the pe size of default of 4mb is 22gb, times 8mb is nearly 45gb. to get near the 150gb mark your going to have to up the pe size to 32mb, by my calculations

5600(pe value) x 32mb(pe size) = 179gb. so this is more than enough for one disk.

If you want to add the disks to one vg though, or more than one disk then you are going to have to increase this further. But its not an ideal situation. 10.20 never had to worry about pv's this size before.

Ideally you would increase the max pe value, but unfortunaley this is not possible like it is in 11.x. In 11.x you can go upto 65535(max_pe). rather than increase the pe size as you end up with wasted space.

Andy

[Matti_Kurkela]

For maximum filesystem sizes, please see this document:
http://docs.hp.com/en/5971-2383/5971-2383.pdf

HP-UX FAQ tells a bit more (see 8.31):
http://www.faqs.org/faqs/hp/hpux-faq/

The supported maximum filesystem size for 10.20 seems to be 128 GB.

Apparently, with some releases & patch levels, you can go up to 256 GB, but the FAQ warns:
"NOTE: Although it may be possible to create files or file systems larger than these documented limits, such files and file systems are not supported, and the results of using them may be unpredictable."

At the moment, I cannot find any document about the limits of the LVM that would include information about 10.20.

MK

[James George_1]

One thing to keep in mind in future to avoid this kind of cituation is that when you create the VG, use the biggest disk first !!

Rgds / James

[Jesse Dougherty]

there was no disk limitation on 10.20, we were able to put 600GB in a J5000 using 10.20. The problem was that we had mislabeled drives, it was a bone-head oversight on our part.

Thanks to everyone who responded, we got some useful information in the process.

Jesse
Cypress Tech