Installing the multi-volume DASD dump tool

This example shows how to perform the dump process on two partitions, /dev/dasdc1 and /dev/dasdd1, which reside on ECKD™ volumes /dev/dasdc and /dev/dasdd.

About this task

Assume that the corresponding device bus-IDs (as displayed by lsdasd) are 0.0.4711 and 0.1.4712.

Procedure

Format both dump volumes with dasdfmt. The command shown uses the default cdl (compatible disk layout) and specifies a block size of 4KB.
```
# dasdfmt -f /dev/dasdc -b 4096
# dasdfmt -f /dev/dasdd -b 4096
```
Create the partitions with fdasd. The sum of the partition sizes must be sufficiently large (the memory size + 10 MB):
```
# fdasd /dev/dasdc
# fdasd /dev/dasdd
```
Create a file named mvdump.conf containing the device nodes of the two partitions, separated by one or more line feed characters (0x0a). The file's contents are as follows:
```
/dev/dasdc1
/dev/dasdd1
```

Prepare the volumes using the zipl command. Specify the dump list on the command line.

Command line example:

# zipl -M mvdump.conf
 Dump target: 2 partitions with a total size of 1234 MB. 
 Warning: All information on the following partitions will be lost! 
 /dev/dasdc1 
 /dev/dasdd1 
 Do you want to continue creating multi-volume dump partitions (y/n)?

Results

Now the two volumes /dev/dasdc and /dev/dasdd with device numbers 0.0.4711 and 0.1.4712 are prepared for a multi-volume dump. Use the --device option of zgetdump to display information about these volumes:

# zgetdump -d /dev/dasdc
Dump device info:
  Dump tool.........: Multi-volume DASD dump tool
  Version...........: 2
  Architecture......: s390x (64 bit)
  Dump size limit...: none
  Force specified...: no

  Volume 0: 0.0.4711 (online/valid)
  Volume 1: 0.1.4712 (online/valid)

During zipl processing both partitions were earmarked for dump with a valid dump signature. The dump signature ceases to be valid when data other than dump data is written to the partition. For example, writing a file system to the partition overwrites the dump signature. Before writing memory to a partition, the dump tool checks the partition's signature and exits if the signature is invalid. Thus any data inadvertently written to the partition is protected.

You can circumvent this protection, for example, if you want to use a swap space partition for dumping, by using the zipl command with the --force option. This option inhibits the dump signature check, and any data on the device is overwritten. Exercise great caution when using the force option.

The zipl command also takes a size specification, see Obtaining a dump with limited size.