Multipathd testing

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  1. Format and mount the SAN LUN.
  2. Start a write to the mounted filesystem cat /dev/zero >> /pathto/mnt/testfile &
  3. Now connect to the multipath daemon in interactive mode multipathd -k
  4. View current paths with show maps topology

    multipathd> show maps topology reload: mpath5 (360060e801045249004f2a5f900000031) dm-7 HITACHI,DF600F [size=128G][features=0][hwhandler=0][rw] _ round-robin 0 [prio=1][active] _ 1:0:0:4 sdb 8:16 [active][ready] _ round-robin 0 [prio=0][enabled] _ 2:0:0:4 sdc 8:32 [active][ready]

  5. There are two paths shown as sdb and sdc. Delete one path. del path sdb

  6. Suspend with ctrl-z and check that the write is still happening. ls -l /pathto/mnt If testfile is still growing then the path sdc is working.
  7. Resume multipath with fg 2. Re-add the path. add path sdb
  8. Now remove the other path. del path sdc
  9. Again suspend iwth ctrl-z and check that the test file is growing. If so then resume multipath and re-add the path. add path sdc
  10. Testing complete. Exit with ctrl-c. Kill the write job with kill %1. Remove the test file.

GNU Screen cheatsheet

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