HP Storage Mirroring V5.1 Software - Manual (Page 41)

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Replication capabilities
Storage Mirroring replicates file and directory data stored on any Windows file system (FAT, FAT32,
NTFS4, and NTFS5). Replicated items also include Macintosh ® files, compressed files, NTFS attributes
and ACLs (access control list), dynamic volumes, files with alternate data streams, sparse files, and
encrypted files. Files can be replicated across mount points, even though mount points are not
created on the target. Some reparse points are replicated, including CommVault ® Data Migrator and
BridgeHead Software HT FileStore.
Storage Mirroring does not replicate items that are not stored on the file system, such as physical
volume data and registry based data. Addtionally, Storage Mirroring does not replicate NTFS
extended attributes, registry hive files, Windows or any system or driver pagefile, system metadata
files ($LogFile, $Mft, $BitMap, $Extend\\$UsnJrnl, $Extend\\$Quota, $Extend\\$ObjId, and
$Extend\\$Reparse), hard links, or the Storage Mirroring disk-based queue logs. The only exception
to these exclusions is for the Storage Mirroring full-server products. If you are protecting your system
state and data using a full-server product, Storage Mirroring will automatically gather and replicate
all necessary system state data, including files for the operating system and applications.
Note the following replication caveats.
1. If you have mixed file systems, keep in the mind the following.
a. If, on your source, you have a FAT volume mounted on a directory which resides on an NTFS
volume, these files will not be mirrored, regardless of the target file system. Replication will
work correctly. To work around this issue, make sure both volumes are NTFS.
b. If you are mirroring/replicating from an NTFS source to a FAT target, you may see additional
error messages in your Storage Mirroring log file because the target file system cannot
handle the NTFS attributes or file permissions. For example, if your replication set contains
files with alternate data streams, you will see messages indicating that there are unfinished
operations because the FAT file system cannot store the alternate data stream information.
c. If you select a compressed file or folder from an NTFS partition and replicate it to a FAT
target, the attributes are lost, but the data is maintained.
2. If any directory or file contained in your replication set specifically denies permission to the
system account or the account running the Storage Mirroring service, the attributes of the file on
the target will not be updated because of the lack of access. This also includes denying
permission to the Everyone group because this group contains the system account.
3. If you select a dynamic volume and you increase the size of the volume, the target must be able
to compensate for an increase in the size of the dynamic volume.
4. If you select files with alternate data streams, keep in mind the following.
a. Alternate data streams are not included in the replication set size calculation. Therefore, you
may see the mirror process at 100% complete while mirroring continues.
b. The number of files and directories reported to be mirrored will be incorrect. It will be off by
the number of alternate streams contained in the files and directories because the alternate
streams are not counted. This is a reporting issue only. The streams will be mirrored
correctly.
c. Use the checksum option when performing a difference mirror or verification to ensure that
all alternate data streams are compared correctly.
d. If your alternate streams are read-only, the times may be flagged as different if you are
creating a verification report only. Initiating a remirror with the verification will correct this
issue.
5. If you select encrypted files, keep in mind the following.
a. Only the data, not the attributes or security/ownership, is replicated. However, the
encryption key is included. This means that only the person who created the encrypted file
on the source will have access to it on the target.
b. Only data changes cause replication to occur; changing security/ownership or attributes does
not.
c. Replication will not occur until the Windows Cache Manager has released the file. This may
take awhile, but replication will occur when Storage Mirroring can access the file.
d. When remirroring, the entire file is transmitted every time, regardless of the remirror
settings.
e. Verification cannot check encrypted files because of the encryption. If remirror is selected,
the entire encrypted file will be remirrored to the target. Independent of the remirror option,
all encrypted files will be identified in the verification log.