Managing Systems and Workgroups: A Guide for HP-UX System Administrators

Administering a System: Managing Disks and Files

Managing Disks

Chapter 6592

So, suppose you wish to stripe across three disks. You decide on a

stripe size of 32 kilobytes. Your logical volume size is 24 megabytes.

To create the striped logical volume, you would enter:

lvcreate -i 3 -I 32 -L 24 -n lvol1 /dev/vg01

lvcreate automatically rounds up the size of the logical volume to a

multiple of the number of disks times the extent size.

For example, if you have three disks you wish to stripe across and

choose the default of 4MB extents, even though you indicate a logical

volume size of 200 (-L 200), lvcreate will create a 204MB logical

volume since 200 is not a multiple of 12.

NOTE When you stripe across multiple disks, the striped volume size

cannot exceed the capacity of the smallest disk multiplied by the

number of disks used in the striping.

For guidelines on determining an optimum stripe size, see

“Determining Optimum Stripe Size” on page 592.

Determining Optimum Stripe Size The logical volume’s stripe size

identiﬁes the size of each of the blocks of data that make up the stripe.

You can set the stripe size to four, eight, 16, 32, or 64 kilobytes (KB) (the

default is eight KB).

NOTE The stripe size of a logical volume is not related to the physical sector

size of a disk, which is typically 512 bytes.

How you intend to use the striped logical volume determines what stripe

size you assign to it.

For best results:

• If you plan to use the striped logical volume for an HFS ﬁle system:

Select the stripe size that most closely reﬂects the block size of the

ﬁle system. The newfs command lets you specify a block size when

you build the ﬁle system and provides a default block size of eight KB

for HFS.