HP StorageWorks 8000, Руководство пользователя

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Managing Your Storage
138 HP StorageWorks NAS 8000 User’s Guide
6. Enter the maximum size for the snapshot volume in the Snapshot Capacity
field. A snapshot must be larger than the minimum file volume size and
smaller than the file volume itself. Of course, if there is not enough space left
in the volume group, the snapshot maximum size is limited by the space
available in the volume group. The default snapshot capacity is 10 percent the
size of the file volume being snapped.
7. In the Snapshot Capacity Policy box, select either:
— Auto Grow at and select a percentage from the drop-down list to allow
the snapshot to grow automatically if it is almost full. Allow a sufficiently
large margin in the autogrow configuration. If a snapshot becomes full,
the NAS 8000 has no place to write the old blocks from the logical
volume as they change, so the snapshot is no longer a true snapshot. It is
therefore invalidated and dropped. At this point, the Command View NAS
interface will not allow any further use/manipulation of the snapshot. The
only recourse is to delete the snapshot.
Note: When you create a snapshot of a file volume, it initially consumes
no physical space. However, as users modify the file volume, the snapshot
tracks changes between the original file volume and the modified file
volume. So, for every file that changes, snapshot capacity is consumed.
You want to specify a large enough capacity so that an original copy of all
files that change is saved, but not so large that the snapshot volume takes
up a lot of valuable storage space. You can always resize a snapshot at a
later time.
— Send Notification at and select a percentage from the drop-down list to
send an SNMP alert when the space used on a snapshot volume reaches a
certain percentage. When data is written to the new snapshot, the
available space in the snapshot volume decreases. Note: This percentage
is used in conjunction with the settings you entered on the SNMP alert,
email, and syslog configuration pages. If you do not set a trap destination
or email address, no notification will be sent.
8. In the Snapshot Expiration Policy box, select one of the following:
— Never if you don’t want this snapshot to be automatically deleted. If you
select this option, you must delete the snapshot manually.
— On This Date and specify a date and time for the snapshot to be deleted.
— After and specify a day, week, or month value.
9. Click OK to create the snapshot and close the dialog box.