Identifying The Storage Area; Determining Creation Frequency; Shadow Copies And Drive Defragmentation - HP StoreEasy 1000 Administrator's Manual

NOTE: Regardless of the volume space that is allocated for shadow copies, there is a maximum
of 64 shadow copies for any volume. When the 65th shadow copy is taken, the oldest shadow
copy is purged.
The minimum amount of storage space that can be specified is 350 megabytes (MB). The default
storage size is 10 percent of the source volume (the volume being copied). If the shadow copies
are stored on a separate volume, change the default to reflect the space available on the storage
volume instead of the source volume. Remember that when the storage limit is reached, older
versions of the shadow copies are deleted and cannot be restored.
CAUTION:
change history that is kept on the original storage volume is lost. To avoid this problem, verify
that the storage volume that is initially selected is large enough.

Identifying the storage area

To store the shadow copies of another volume on the same file server, a volume can be dedicated
on separate disks. For example, if user files are stored on H:\, another volume such as S:\can
be used to store the shadow copies. Using a separate volume on separate disks provides better
performance and is recommended for heavily used HPE StoreEasy 1000 Storage systems.
If a separate volume will be used for the storage area (where shadow copies are stored), the
maximum size must be changed to No Limit to reflect the space available on the storage area
volume instead of the source volume (where the user files are stored).
Disk space for shadow copies can be allocated on either the same volume as the source files
or a different volume. There is a trade-off between ease of use and maintenance versus
performance and reliability that the system administrator must consider.
By keeping the shadow copy on the same volume, there is a potential gain in ease of setup and
maintenance; however, there may be a reduction in performance and reliability.
CAUTION:
of disk input/output (I/O) can cause all shadow copies to be deleted. If the sudden deletion of
shadow copies is unacceptable to administrators or end users, it is best to use a separate volume
on separate disks to store shadow copies.

Determining creation frequency

The more frequently shadow copies are created, the more likely that end users will get the version
that they want. However, with a maximum of 64 shadow copies per volume, there is a trade-off
between the frequency of making shadow copies and the amount of time that the earlier files will
be available.
By default, the HPE StoreEasy 1000 Storage system creates shadow copies at 0700 and 1200,
Monday through Friday. However, these settings are easily modified by the administrator so that
the shadow copy schedule can better accommodate end user needs.

Shadow copies and drive defragmentation

When running Disk Defragmenter on a volume with shadow copies activated, all or some of the
shadow copies may be lost, starting with the oldest shadow copies.
If defragmenting volumes on which shadow copies are enabled, use a cluster (or allocation unit)
size of 16 KB or larger. Using this allocation unit size reduces the number of copy outs occurring
on the snapshot. Otherwise, the number of changes caused by the defragmentation process can
cause shadow copies to be deleted faster than expected. Note, however, that NTFS compression
is supported only if the cluster size is 4 KB or smaller.
To change the storage volume, shadow copies must be deleted. The existing file
If shadow copies are stored on the same volume as the user files, note that a burst
Volume shadow copies 127