Disk Space Needs; Dump Level; Compressed Save Vs. Noncompressed Save - HP 9000 V-Class Operator's Manual

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Recovering from failures

Abnormal system shutdowns

Disk space needs

This section discusses how to manage limited disk resources on your

system for the post-crash dump and/or the post-reboot save of the

memory image. The factors to consider are:

• Partial save (savecrash -p)

Dump level

There are three levels of core dumps: full dump. selective dump, and no

dump. The fewer pages required to dump, the less space is required to

hold them. Therefore, a full dump is not recommended. If disk space is

really at a premium, one option is no dump at all.

A third option is called a selective dump. HP-UX 11.0 can determine

which pages of memory are the most critical for a given type of crash,

and save only those pages. Choosing this option can save a lot of disk

space on the dump devices and again later on the HP-UX ﬁle system

area. For instructions on how to do this see "Deﬁning dump devices" on

page 88.

Compressed save vs. noncompressed save

Regardless of whether you choose full or selective dump, whatever is

saved on the dump devices needs to be copied to the HP-UX ﬁle system

area before you can use it.

NOTE

With HP-UX 11.0, it is possible to analyze a crash dump directly from

dump devices using a debugger that supports this feature. If, however,

you need to save it to tape or send it to someone, copy the memory image

to the HP-UX ﬁle system area ﬁrst.

If there is a disk space shortage in the HP-UX ﬁle system area (as

opposed to dump devices), you can elect to have savecrash (the boot

time utility that does the copy) compress your data as it makes the copy.

Chapter 7

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