This chapter discusses the following:
The following operations take place when booting a CXFS cluster that includes XVM volumes:
The system boots and probes all disks (SGI SAN disks and FC-hub disks, internal SCSI, and so on).
A boot script initiates the reading of all the labels and creates a view of all local volumes. Cluster volumes are not visible at this point.
The cluster is initialized.
On each node in the cluster, XVM reads all of the labels on the disk and creates a cluster-wide view of all volumes including the third-party SAN volumes.
A mirror revive is the process of synchronizing data on the members of a mirror. A mirror revive is initiated at the following times:
A mirror with more than one leg is initially constructed
A leg is attached to a mirror
The system is booted with mirrors that are not synchronized
A node in a CXFS cluster crashes when the mirror is open (see “Slow Mirror Revives” in Chapter 11)
A message is written to the system log when a mirror begins reviving. Another message is written to the system log when this process is complete. If the revive fails, a message is written to the system console and the system log.
For large mirror components, the process of reviving may take a long time. You cannot halt a mirror revive once it has begun except by detaching all but one of the legs of the mirror.
There are some mirrors that may not need to revive on creation or when the system reboots. For information on creating these mirrors, see “Mirror Revive at Creation” in Chapter 2 and “Mirror Revive at Reboot” in Chapter 2.
While a mirror is in the process of reviving, you can configure the volume that contains the mirror and you can perform I/O to the mirror. Displaying the mirror volume element with the show command will show the percentage of the mirror blocks that have been synchronized.
If a mirror revive is required while a previously-initiated mirror revive is still occurring, the mirror revive can be queued; this is displayed as the state of the mirror when you display its topology.
You can modify the system performance of mirror revives with the XVM system tunable parameters. For more information, see:i