HP ProLiant ML310 G3 Storage Server Administration Guide (WSS R2 version, March 2006)

Identifying the volume

Shadow copies are taken for a complete volume, but not for a speciﬁcdirectory. Shadowcopies

work best when th

eserverstoresuserﬁles, such as documents, spreadsheets, presentations, graphics,

or database ﬁle

NOTE:

Shadow copies should not be used to provide access to previous versions of application or e-mail

databases.

Shadow copies are designed for volumes that store user data such as home d irectories and My Documents

folders that are redirected by using Group P olicy or other shared folders in which users store data.

Shadow copies work with compressed or encrypted ﬁles a nd retain whatever permissions were set on the

ﬁles when the shadow copies were taken. For example, if a user is denied permission to read a ﬁle,

that user would not be able to restore a previous version of the ﬁle, or be able to read the ﬁle after

it has been restored.

Although shadow copies are taken for an entire volume, users must use shared folders to access shadow

copies. Administrators on the local server must also specify the \\servername\sharename path to

access shadow copies. If administrators or end users want to access a previ ous version of a ﬁle that does

not reside in a shared folder, the administrator must ﬁrstsharethefolder.

NOTE:

Shadow c opies are available only on NTFS, not FAT or FAT32 volumes.

Files or folders that are recorded by using Shadow Copy appear static, even though the original d ata is

changing.

Allocating disk space

When determining the amount of space to allocate for storing shadow copies, consider both the number

and size of ﬁles that are being copied, as well as the frequency of changes between copies. For

example, 100 ﬁles that only change monthly require less storage space than 10 ﬁles that change daily. If

the frequency of changes to each ﬁle is greater than the amount of space alloca ted to storing shadow

copies, no shadow copy is created.

Administ

rators should also consider user expectations of how many versions they will want to have

available. End users might expect only a single shadow copy to be available, or they might expect three

days or three weeks worth of sha dow copies. The more shadow copies users expect, the more storage

space a dministrators must a llocate for storing them.

Setting the limit too low also affects backup programs that use shadow copy technology because these

programs are also limited to using the amount of disk space speciﬁed by administrators.

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 reﬂectthespaceavailableonthestorage volume instead of the

source volume. Remember that when the storage limit is reached, older versions of the shadow copies

are deleted and c annot be restored.

HP ProLiant ML310 G3 Storage Server administration guide