Seagate ST34572WC Especificaciones descargar pdf (Pagina 6)

# swlist -l fileset | grep -i mirror

LVM.LVM-MIRROR-RUN B.11.23 LVM Mirror

The process of mirroring is usually straightforward, and can be easily accomplished using the system

administration manager SAM, or with a single lvextend command. These processes are

documented in Managing Systems and Workgroups (11i v1 and v2) and System Administrator's

Guide: Logical Volume Management (11i v3). The only mirroring setup task that takes several steps is

mirroring the root disk. See Appendix D for the recommended procedure to add a root disk mirror. .

There are three corollaries to the mirroring recommendation:

1. Use the strict allocation policy for all mirrored logical volumes. Strict allocation forces mirrors to

occupy different disks. Without strict allocation, you can have multiple mirror copies on the same

disk; if that disk fails, you will lose all your copies. To control the allocation policy, use the –s

option with the lvcreate and lvchange commands. By default, strict allocation is enabled.

2. To improve the availability of your system, keep mirror copies of logical volumes on separate I/O

busses if possible. With multiple mirror copies on the same bus, the bus controller becomes a

single point of failure—if the controller fails, you lose access to all the disks on that bus, and thus

access to your data. If you create physical volume groups and set the allocation policy to PVG-

strict, LVM helps you avoid inadvertently creating multiple mirror copies on a single bus. For more

information about physical volume groups, see lvmpvg(4).

3. Consider using one or more free disks within each volume group as spares. If you configure a disk

as a spare, then a disk failure causes LVM to reconfigure the volume group so that the spare disk

takes place of the failed one. That is, all the logical volumes that were mirrored on the failed disk

are automatically mirrored and resynchronized on the spare, while the logical volume remains

available to users. You can then schedule the replacement of the failed disk at a time of minimal

inconvenience to you and your users. Sparing is particularly useful for maintaining data

redundancy when your disks are not hot-swappable, since the replacement process may have to

wait until your next scheduled maintenance interval. Disk sparing is discussed in Managing

Systems and Workgroups (11i v1 and v2) and System Administrator's Guide: Logical Volume

Management (11i v3).

Note: The sparing feature is one where you can use a spare physical volume to replace an existing

physical volume within a volume group when mirroring is in effect, in the event the existing physical

volume fails. The sparing feature is available for version 1.0 volume groups (legacy volume group).

Version 2.x volume groups do not support sparing.

Creating Recovery Media

Ignite/UX lets you create a consistent, reliable recovery mechanism in the event of a catastrophic

failure of a system disk or root volume group. You can back up essential system data to a tape

device, CD, DVD, or a network repository, and quickly recover the system configuration. While

Ignite/UX is not intended to be used to back up all system data, you can use it with other data

recovery applications to create a means of total system recovery.

Ignite/UX is a free add-on product, available from www.hp.com/go/softwaredepot. Documentation

is available from the Ignite/UX website.

Other Recommendations for Optimal System Recovery

Here are some other recommendations, summarized from the Managing Systems and Workgroups

and System Administrator's Guide: Logical Volume Management manuals that simplify recoveries

after catastrophic system failures:

• Keep the number of disks in the root volume group to a minimum (no more than three), even if the

root volume group is mirrored. The benefits of a small root volume group are threefold: First, fewer

disks in the root volume group means less opportunities for disk failure in that group. Second, more

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