Create Snapshot Virtual Disk Wizard: Additional Instructions for HP-UX - LVM Logical Virtual Disks

Use the following procedure to create on a running HP-UX 11.0 (or higher) using LVM logical virtual disks. Failure to complete the steps listed might result in an inaccurate point-in-time image of the source virtual disk.

For a process overview of the snapshot virtual disk creation process, refer to Create Snapshot Virtual Disk Wizard: Process Overview - UNIX with Virtual Disk Manager Virtual Disks.

Snapshot virtual disks might be reused (for frequent or nightly backups) or may be created for one-time usage (speculative change or upgrade testing). For instructions on how to reuse a disabled snapshot virtual disk, see Reusing Snapshot Virtual Disks.

Creating a Snapshot Virtual Disk

Use the following procedure to create a snapshot virtual disk.

Start the storage management software.

Launch an by selecting the in either the Tree view or the Table view and selecting Tools >> Manage Device.

The Array Management Window is opened in a separate window.

Important: Stop the host application accessing the and unmount the source virtual disk. Unmounting the source virtual disk does not apply when the source virtual disk is the root disk of the .

When creating a snapshot virtual disk based on a mounted file system, always perform a synchronization to flush the file system cache immediately prior to creating a snapshot virtual disk.

At the host prompt, type the following command, and press Enter:

sync

All unwritten file system buffers are flushed.

Within the Logical View of the Array Management Window, select a , and create a snapshot virtual disk using one of the following methods:

Create Snapshot Virtual Disk Wizard, accessed using an Array Management Window. For more information, see Creating a Snapshot Virtual Disk Using the Snapshot Virtual Disk Wizard.
Create a snapshot virtual disk using either the Script Editor or a command line shell on the host type. Type the following command, and press Enter:

create snapshotVirtual Disk

For command reference information on creating a snapshot virtual disk, refer to the Enterprise Management Window online help.

Assign a between the snapshot virtual disk and the host that will access the snapshot virtual disk. You can define virtual disk-to-LUN mappings by using one of the following methods:

Storage Partitioning Wizard, which helps you to quickly define a single . It guides you through the major steps required to specify which host will access a virtual disk, and the associated . For more information, see Using the Storage Partitioning Wizard.
Create a virtual disk-to-LUN mapping using either the Script Editor or a command line shell on the host type. Type the following command, and press Enter:

create mapping virtual disk

For command reference information on creating a virtual disk-to-LUN mapping, refer to the Enterprise Management Window online help.

Disable the snapshot virtual disk using one of the following methods:

Select Virtual Disk >> Snapshot >> Disable in the Array Management Window. For more information, see Disabling a Snapshot Virtual Disk.
Disable a snapshot virtual disk using either the Script Editor or a command line shell on the host type. Type the following command, and press Enter:

disableSnapshot virtual disk

For command reference information on disabling a snapshot virtual disk, refer to the Enterprise Management Window online help.

At the host prompt, type the following command, and press Enter:

ioscan -fn

A list of the mapped devices recognized by the host is displayed.

Note: If the required device names are not displayed using the above command, at the host prompt, type the following, then press Enter:

insf

Unmount the source virtual disk.

In the storage management software, re-create the snapshot virtual disk by using one of the following methods:

Select Virtual Disk >> Snapshot >> Re-create in the Array Management Window. For more information, see Re-creating a Snapshot Virtual Disk.
Re-create a snapshot virtual disk using either the Script Editor or a command line shell on the host type. Type the following command, and press Enter:

recreateSnapshot virtual disk

For command reference information on recreating a snapshot virtual disk, refer to the Enterprise Management Window online help.

Remount the source virtual disk (to its original host).

Important: If I/O activity to the source virtual disk was stopped or data transfer was suspended, resume I/O activity to the source virtual disk at this time (or re-enable data transfer).

Complete the following steps to import the snapshot virtual disks into the Logical Virtual Disk Manager.

a	Create a new directory for the new . Example: `mkdir /dev/vg02`
b	Create a group node for the new disk group. Example: `mknod /dev/vg02/group c 64 -0x020000`
c	Import the snapshot virtual disk LUNs. At the host prompt, type the following, then press Enter: `vgimport /dev/vg02 snapshot-block-node-1 snapshot-block-node-2` Example: `vgimport /dev/vg02 /dev/dsk/c66t0d1 /dev/dsk/c69t0d1` Note: Verify `/dev/dsk` device files to be the snapshot virtual disk and that they exist using the utility or the HP-UX `ioscan` utility. A warning is displayed indicating that a backup of the disk group being imported might not exist on the host. This message is only a warning, and can be ignored. The import will continues and completes successfully. The backup for this disk group is created when it is later exported.
d	Activate the new disk group. Example: `vgchange -a y /dev/vg02`

If a file system existed on the source virtual disk, then it will also exist on the snapshot virtual disk. However, before the snapshot virtual disk can be mounted, run a file system check to ensure that the file system is consistent.

Example:

fsck /dev/vg02/lvol01

Mount the snapshot virtual disk to its intended host.

Use the snapshot virtual disk with your backup application, for speculative testing, or with another application.

Unmount the snapshot virtual disk.

After the snapshot virtual disk is no longer required, disable the snapshot virtual disk.

If you disable the snapshot virtual disk instead of deleting it, you can retain the snapshot virtual disk and its associated . Then, when you need to create a different snapshot of the same source virtual disk, you can re-create the disabled snapshot virtual disk. This action takes less time than creating a new snapshot virtual disk and stops any reduction in performance that might occur if the snapshot virtual disk remains available.

For information on disabling or re-creating a snapshot, see Disabling a Snapshot Virtual Disk and Re-creating a Snapshot Virtual Disk. For information on deleting a snapshot virtual disk, see Deleting a Virtual Disk.

For command reference information on disabling, re-creating, and deleting a snapshot virtual disk, refer to the Enterprise Management Window online help.

Reusing Snapshot Virtual Disks

Typically, after a snapshot virtual disk has been created it, would be disabled until a new point-in-time image of the same source virtual disk is required. Use the following procedure to create a new point-in-time image of the same source virtual disk.

Important: All I/O activity to the source virtual disk should be stopped at this point (or data transfer suspended). This will ensure that an accurate point-in-time image of the source virtual disk is captured.

Unmount the source virtual disk.

In the storage management software, re-create the snapshot virtual disk by using one of the following methods:

Select Virtual Disk >> Snapshot >> Re-create in the Array Management Window. For more information see Re-creating a Snapshot Virtual Disk.
Re-create a snapshot virtual disk using either the Script Editor or a command line shell on the host type. Type the following command, and press Enter:

recreateSnapshot virtual disk

For command reference information on re-creating a snapshot virtual disk, refer to the Enterprise Management Window online help.

Remount the source virtual disk (to its original host).

Important: If I/O activity to the source virtual disk was stopped or data transfer was suspended, resume I/O activity to the source virtual disk at this time (or re-enable data transfer).

Complete the following steps to import the snapshot virtual disks into the Logical Virtual Disk Manager.

a	Create a new directory for the new disk group. Example: `mkdir /dev/vg02`
b	Create a group node for the new disk group. Example: `mknod /dev/vg02/group c 64 -0x020000`
c	Import the snapshot virtual disk LUNs. At the host prompt, type the following command, and press Enter: `vgimport /dev/vg02 snapshot-block-node-1 snapshot-block-node-2` Example: `vgimport /dev/vg02 /dev/dsk/c66t0d1 /dev/dsk/c69t0d1` Note: Verify `/dev/dsk` device files to be the snapshot virtual disk and that they exist using the utility or the HP-UX `ioscan` utility. A warning is displayed indicating that a backup of the disk group being imported might not exist on the host. This message is only a warning and can be ignored. The import continues and completes successfully. The backup for this disk group is created when it is later exported.
d	Activate the new disk group. Example: `vgchange -a y /dev/vg02`

If a file system existed on the source virtual disk, then it also exists on the snapshot virtual disk. However, before the snapshot virtual disk can be mounted, run a file system check to ensure that the file system is consistent.

Example:

fsck /dev/vg02/lvol01

Mount the snapshot virtual disk to its intended host.

Use the snapshot virtual disk with your backup application (or other application).

Unmount the snapshot virtual disk.

After the snapshot virtual disk is no longer required, disable the snapshot virtual disk.

If you disable the snapshot virtual disk instead of deleting it, you can retain the snapshot virtual disk and its associated snapshot repository virtual disk. Then, when you need to create a different snapshot of the same source virtual disk, you can re-create the disabled snapshot virtual disk. This takes less time than creating a new snapshot virtual disk and stops any reduction in performance that might occur if the snapshot virtual disk remains available.

For more information, see Disabling a Snapshot Virtual Disk and Re-creating a Snapshot Virtual Disk. For command reference information on disabling and re-creating a snapshot virtual disk, refer to the Enterprise Management Window online help.

Create Snapshot Virtual Disk Wizard: Additional Instructions for HP-UX - LVM Logical Virtual Disks

Creating a Snapshot Virtual Disk

Reusing Snapshot Virtual Disks

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