Dump size limit

[Ninad_1]

Hi All,

The dump configuration section in the HP doc at http://docs.hp.com/en/B2355-90950/ch06s03.html says
CAUTION: To prevent possible file corruption, a dump logical volume (or a swap logical volume used for dump) must lie within the first two GB on the physical volume. The lvlnboot command will not allow a dump logical volume to be configured that exceeds two GB (but it will allow such a swap logical volume to be so configured).

My queries are
1. Is the size of dump device limited to 2 GB ?
2. Does the dump volume need to be within the 1st 2 GB of a physical volume ?
3. When it is recommended that there should be dump space available equal to the physical memory, if I have memory say 32 GB, then does it mean that I need to configure the 1st dump device of only 2 GB which should be withing 2GB of physical volume and configure rest of the 30 GB dump device as secondary dump - dump2 volume elsewhere in the vg00
4. Can the secondary dump devices be greater than 2 GB atleast ? or I need to have several dump devices 2 GB each to make up the total dump space requirement of 32 GB?
5. If the 2GB limit is not what I have understood correctly, is there any other limit on size of a dump logical volume size?

Thanks and regards,
Ninad

[Steven E. Protter · Accepted solution]

Shalom,

1. No. I've never heard of this limit
2. This probably has to do with some old legacy 32 bit rule. I'm curious though.
3. Dumps can be up to half of physical memory. Thats what I'd configure for.

SEP

[A. Clay Stephenson]

Those restrictions applied to older OS versions. If you are 11.x then you can have much larger dump volumes. Bear in mind that multiple dump devices can be configured.

In most cases on systems with large amounts of memory, dump space equal to 25% of memory will more than suffice to capture all needed information for analysis.

I never combine swap and dump but define separate areas for each. This also means that you can turn off savecrash becuase there is no danger of dump being overwritten by swap usage so valuable minutes can be saved during a reboot after a crash. Also, swap should be mirrored and dump should never be mirrored.

[Ninad_1]

Thanks SEP and Clay, as usual you are on of the quickest to respond and help.
I would be having HP-UX 11.11 server and the text in the document does not anywhere specify that the limit mentioned is for a particular version of HP-UX.
In one of the older standard documents we followed, I read a mention of 8GB to be max size for dump so after referring to the HP doc, got more confused.
Just before closing this thread, can you tell me if I can safely assume that there is no limit at all for dump device size.

Also I will follow the other guidelines of configuring around 25% of physical memory and having separate swap and dump volumes.

Thanks,
Ninad

[Ninad_1]

Concluding that logical volume for dump device can be greater than 2 GB for HP-UX 11.11.
Closing the thread.
Thanks,
Ninad