IBM DS flash copy

Introduction

_images/ibmdsflashcopy.png

IBM Flash copy allow multi-target block device replication. After create initial flash copy, the relation can persist. These features allow opensvc to drive services using a flash copy device set. Such services are often used for maintenance, pre-production and performance testing environments, where the source device set is used for production. The following documentation presents the configuration of such a service.

A service with only flash copy sync resources can be defined to drive the clone of other servers, just for the benefit of centralized logging and scheduling.

Command set

sync resync
  • Resyncflash (or rmflash/mkflash) action to pair source/target. This command verifies the service is down before proceeding.
sync resync --force
  • Bypass the sync_min_delay protection.

Status

up
  • The last resync occured less than 'sync_max_delay' minutes ago.
warn
  • The last replication occured more than ‘sync_max_delay’ minutes ago.
  • Device are in a unexpected state or not present in the flash copy persistent pair list.

Service configuration

Pre-requisites

The dscli commands must be installed in the standard location on the nodes running this service resource type.

The array managers credentials must be defined in the node or cluster configuration.

Example:

[array#IBM.XXXX-XXXXXXX]
type = ibmds
hmc1 = 10.10.10.10
hmc2 =
username = opensvc

Use dscli commands to create pwfile in <OSVCVAR>. The pwfile's name must be the same as the array. For exemple <OSVCVAR>/IBM.XXXX-XXXXXXX.pwfile.

Example:

dscli managepwfile -action add -mc1 1.2.3.4 -mc2 1.2.3.5
                   -pwfile /var/lib/opensvc/IBM.2107-00AAA00.pwfile
                   -name opensvc -pw xxx

You can setup as many sync resources as needed to ensure a consistent replication scenario.

IBM DS flash copy configuration

You have to create the persistent flash copy manually once. This requires two existing devices.

Examples

Resync a started service snapshots

# svcmgr -s iiststibmds stop && \
  svcmgr -s iiststibmds sync resync && \
  svcmgr -s iiststibmds start

Resync a stopped service snapshots

# svcmgr -s iiststibmds sync resync
2014-09-18 23:04:02,189 - IISTSTIBMDS.SYNC#1 - INFO - resyncflash - dev IBM.XXXX-XXXXXXX -persist -record -cp 0001:0002 0101:0102 0003:0004 | /opt/ibm/dscli/dscli -hmc1 10.10.10.10 -user opensvc -pwfile /var/lib/opensvc/IBM.XXXX-XXXXXXX.pwfile
2014-09-18 23:04:05,621 - IISTSTIBMDS.SYNC#1 - INFO - Date/Time: September 18, 2014 11:04:04 PM CEST IBM DSCLI Version: 7.7.10.317 DS: IBM.XXXX-XXXXXXX

 Date/Time: September 18, 2014 11:04:04 PM CEST IBM DSCLI Version: 7.7.10.317 DS: IBM.XXXX-XXXXXXX

CMUC00168I resyncflash: FlashCopy volume pair 0001:0002 successfully resynchronized.
CMUC00168I resyncflash: FlashCopy volume pair 0101:0102 successfully resynchronized.
CMUC00168I resyncflash: FlashCopy volume pair 0003:0004 successfully resynchronized.