HP StorageWorks Storage Mirroring user's guide (T2558-96073, February 2008)

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Source
The Source tab contains settings specific to the source module of Storage Mirroring.
 Replication Packets to 1 Mirror Packet—You can specify the ratio of replication packets to mirror packets that are
placed in the source queue. Specify a larger number if you have a busy network that has heavy replication. Also, if you
anticipate increased network activity during a mirror, increase this number so that the replication queue does not get too
large.
 Replicate NT Security by Name—If you are using a Windows domain security model by assigning users at the domain
level, each user is assigned a security ID (SID). When Storage Mirroring replicates a file to the target, the SID is also
replicated. If you are using a Windows local security model by assigning users at the local level, users that appear on
multiple machines each have different SIDs. After a Storage Mirroring file and SID is replicated, a local user will not be
able to access the file because the user’s SID on the target machine is different from the SID that was replicated from the
source machine. Storage Mirroring allows you to replicate Windows permission attributes by local name as well as
security ID (SID). By replicating Windows security by name, you can transmit the owner name with the file. If that user
exists on the target, then the SID associated with the user will be applied to the target file ownership. If that user does
not exist on the target, then the ownership will be unknown. By default, this option is disabled. If you are using a Windows
local security model, you will need to enable this feature so that users can access the data on the target. If you enable this
option, make sure that the same groups and users exist on the target as they do on the source. Otherwise, mirror and
replication speed will be slower while adjustments are made for the missing groups or users.
Enabling this option may have an impact on the rate at which Storage Mirroring can commit data on the target. File
security attributes are sent to the target during mirroring and replication. The target must obtain the security ID (SID)
for the users and groups that are assigned permissions, which takes some time. If the users and groups are not on the
target server, the delay can be substantial. The performance impact enabling this option will have will vary depending on
the type of file activity and other variables. For instance, it will not affect the overall performance of large database files
much (since there is a lot of data, but only a few file permissions), but may affect the performance of user files
significantly (since there are often thousands of files, each with permissions). In general, the performance impact will only
be noticed during mirrors since that is when the target workload is greatest.