Symantec 10551441 - AntiVirus Corporate Edition Administrator's Manual page 142

142 Scanning for viruses and other threats
Configuring scan options
Table 3-9 lists HSM scanning options for Windows 2000 and later.
Table 3-9 Storage migration options (Windows 2000 and later)
Option
Skip offline files
Skip offline and sparse files
Skip offline and sparse files
with a reparse point
Scan resident portions of
offline and sparse files
Scan all files, forcing
demigration (fills drive)
Description
If the offline bit is set, the file is skipped. A small clock
over a file's icon in Windows Explorer indicates that the
offline bit is set. Any application may set the offline bit
without actually placing the file offline.
Some applications set the file sparse bit to indicate that
part of the file is not present on the disk. Because some
HSM products set this bit and others don't, consult your
HSM vendor to verify whether the sparse bit is set.
With a sparse file, a stub of the file remains on the disk
with the majority of the file moved to offline storage.
Some vendors use reparse points. An application that
uses reparse points will also use an appropriate device
driver to manage reparse points in the files.
This is the default Symantec AntiVirus setting because
it is the most reliable for vendors that use reparse
points. Consult your HSM vendor to determine if this
setting is appropriate.
With a reparse point, a portion of the file remains on
disk with the remainder transparently accessed through
an application filter (the device driver).
Symantec AntiVirus identifies resident portions of a
file. If the file is sparse, only the resident portion is
scanned; the nonresident portion remains in secondary
storage.
Because some vendors support this capability and
others do not, consult your HSM vendor to determine if
this setting is appropriate.
The entire file is scanned, which forces demigration
from secondary storage if necessary. Because the size of
the secondary storage is usually greater than the size of
the local volume, this setting may fill the local volume
and cause further files that are opened for scanning to
fail.