When you add a new disk to a disk set, Solaris Volume Manager checks the disk format and, if necessary, repartitions the disk to ensure that the disk has an appropriately configured slice 7 with adequate space for a state database replica. The precise size of slice 7 depends on the disk geometry, but it will be no less than 4 Mbytes, and probably closer to 6 Mbytes (depending on where the cylinder boundaries lie).
The minimal size for slice seven will likely change in the future, based on a variety of factors, including the size of the state database replica and information to be stored in the state database replica.
For use in disk sets, disks must have a slice seven that meets these criteria:
Starts at sector 0
Includes enough space for disk label and state database replicas
Cannot be mounted
Does not overlap with any other slices, including slice two
If the existing partition table does not meet these criteria, Solaris Volume Manager will repartition the disk. A small portion of each disk is reserved in slice 7 for use by Solaris Volume Manager. The remainder of the space on each disk is placed into slice 0. Any existing data on the disks is lost by repartitioning.
After you add a disk to a disk set, you may repartition it as necessary, with the exception that slice 7 is not altered in any way.
The minimum size for slice seven is variable, based on disk geometry, but is always equal to or greater than 4MB.
The following output from the prtvtoc command shows a disk before it is added to a disk set.
[root@lexicon:apps]$ prtvtoc /dev/rdsk/c1t6d0s0 * /dev/rdsk/c1t6d0s0 partition map * * Dimensions: * 512 bytes/sector * 133 sectors/track * 27 tracks/cylinder * 3591 sectors/cylinder * 4926 cylinders * 4924 accessible cylinders * * Flags: * 1: unmountable * 10: read-only * * First Sector Last * Partition Tag Flags Sector Count Sector Mount Directory 0 2 00 0 4111695 4111694 1 3 01 4111695 1235304 5346998 2 5 01 0 17682084 17682083 3 0 00 5346999 4197879 9544877 4 0 00 9544878 4197879 13742756 5 0 00 13742757 3939327 17682083 |
If you have disk sets that you upgraded from Solstice DiskSuite software, the default state database replica size on those sets will be 1034 blocks, not the 8192 block size from Solaris Volume Manager. Also, slice 7 on the disks that were added under Solstice DiskSuite will be correspondingly smaller than slice 7 on disks that were added under Solaris Volume Manager.
After you add the disk to a disk set, the output of prtvtoc looks like the following:
[root@lexicon:apps]$ prtvtoc /dev/rdsk/c1t6d0s0 * /dev/rdsk/c1t6d0s0 partition map * * Dimensions: * 512 bytes/sector * 133 sectors/track * 27 tracks/cylinder * 3591 sectors/cylinder * 4926 cylinders * 4924 accessible cylinders * * Flags: * 1: unmountable * 10: read-only * * First Sector Last * Partition Tag Flags Sector Count Sector Mount Directory 0 0 00 10773 17671311 17682083 7 0 01 0 10773 10772 [root@lexicon:apps]$ |
If disks you add to a disk set have acceptable slice 7s (that start at cylinder 0 and that have sufficient space for the state database replica), they will not be reformatted.