Seagate ST34572WC Especificaciones descargar pdf (Pagina 4)

1. Preparing for Disk Recovery

Forewarned is forearmed. Knowing that hard disks will fail eventually, you can take some

precautionary measures to minimize your downtime, maximize your data availability, and simplify the

recovery process. Consider the following guidelines before you experience a disk failure.

Defining a Recovery Strategy

As you create logical volumes, choose one of the following recovery strategies. Each choice strikes a

balance between cost, data availability, and speed of data recovery.

 Mirroring: If you mirror a logical volume on a separate disk, the mirror copy is online and

available while recovering from a disk failure. With hot-swappable disks, users will have no

indication that a disk was lost.

 Restoring from backup: If you choose not to mirror, make sure you have a consistent backup

plan for any important logical volumes. The tradeoff is that you will need fewer disks, but you will

lose time while you restore data from backup media, and you will lose any data changed since

your last backup.

 Initializing from scratch: If you do not mirror or back up a logical volume, be aware that you

will lose data if the underlying hard disk fails. This can be acceptable in some cases, such as a

temporary or scratch volume.

Using Hot-Swappable Disks

The hot-swap feature implies the ability to remove or add an inactive hard disk drive module to a

system while power is still on and the SCSI bus is still active. In other words, you can replace or

remove a hot-swappable disk from a system without turning off the power to the entire system.

Consult your system hardware manuals for information about which disks in your system are hot-

swappable. Specifications for other hard disks are available in their installation manuals at

http://docs.hp.com.

Using Alternate Links (PVLinks)

On all supported HP-UX releases, LVM supports Alternate Links to a device to enable continuous

access to the device if the primary link fails. This multiple link or multipath solution increases data

availability, but does not allow the multiple paths to be used simultaneously. In such cases, the device

naming model used for the representation of the mass storage devices is called the legacy naming

model.

Starting with the HP-UX 11i v3 release, there is a new feature introduced in the Mass Storage

Subsystem that also supports multiple paths to a device and allows access to multiple paths

simultaneously. The device naming model used in this case to represent the mass storage devices is

called the agile naming model. The management of the multipathed devices is available outside of

LVM using the next generation mass storage stack. Agile addressing creates a single persistent DSF

for each mass storage device regardless of the number of hardware paths to the disk. The mass

storage stack in HP-UX 11i v3 uses this agility to provide transparent multipathing. When the new

mass storage subsystem multipath behavior is enabled on the system (HP-UX 11i v3 and later), the

mass storage subsystem balances the I/O load across the valid paths.

You can enable and disable the new mass storage subsystem multipath behavior and disabled

through the use of the scsimgr command. For more information, see scsimgr(1M).

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Seagate ST34572WC Especificaciones Pagina 4