HP Veritas Volume Manager 5.0 -UX 11i v3 Specifying ordered allocation of storage to volumes

Creating volumes

Creating a volume on specific disks

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Specifying ordered allocation of storage to volumes

Ordered allocation gives you complete control of space allocation. It requires that the number of disks that you specify to the vxassist command must match the number of disks that are required to create a volume. The order in which you specify the disks to vxassist is also significant.

If you specify the -o ordered option to vxassist when creating a volume, any storage that you also specify is allocated in the following order:

1Concatenate disks.

2Form columns.

3Form mirrors.

For example, the following command creates a mirrored-stripe volume with 3 columns and 2 mirrors on 6 disks in the disk group, mydg:

#vxassist -b -g mydg -oordered make mirstrvol 10g \ layout=mirror-stripe ncol=3 \

mydg01 mydg02 mydg03 mydg04 mydg05 mydg06

This command places columns 1, 2 and 3 of the first mirror on disks mydg01, mydg02 and mydg03 respectively, and columns 1, 2 and 3 of the second mirror on disks mydg04, mydg05 and mydg06 respectively. This arrangement is illustrated in Figure 7-1.

Figure 7-1	Example of using ordered allocation to create a mirrored-stripe
	volume

Column 1	Column 2	Column 3	Striped plex
mydg01-01	mydg02-01	mydg03-01
			Mirror
Column 1	Column 2	Column 3	Striped plex
mydg04-01	mydg05-01	mydg06-01
			Mirrored-stripe
			volume

For layered volumes, vxassist applies the same rules to allocate storage as for non-layered volumes. For example, the following command creates a striped- mirror volume with 2 columns:

#vxassist -b -g mydg -o ordered make strmirvol 10g \ layout=stripe-mirror ncol=2 mydg01 mydg02 mydg03 mydg04

This command mirrors column 1 across disks mydg01 and mydg03, and column 2 across disks mydg02 and mydg04, as illustrated in Figure 7-2.