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

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Calculating replication set size
While Storage Mirroring is mirroring, the right pane of the Management Console displays statistics to keep you informed of
its progress. If the size of the replication set is determined before the mirror is started, Storage Mirroring can display the
percentage of the replication set that has been mirrored in the
Mirror Status column. If the size was not calculated prior to
starting the mirror, the column displays Mirroring.
1. Right-click on the replication set icon and select Properties. The Replication Set Properties dialog box appears.
2. Select the Size tab.
3. If the replication set size has never been determined, click Calculate. If the replication set has previously been
determined, the button will be labeled
Recalculate. Depending on user activity, the size shown may not accurately
reflect the current size of the replication set. If changes are occurring to files in the replication set while the calculation
is being made, the actual size may differ slightly. The amount of data is determined at the exact time the calculation is
made.
4. Click OK to return to the Management Console.
NOTE: You can also configure the replication set calculation when establishing a connection through the Connection
Manager by selecting Calculate Replication Set size on connection on the Mirroring tab.
If your replication set contains a large number of files, for example, ten thousand or more, you may want to
disable the calculation of the replication set size so that data will start being mirrored sooner. If calculation is
enabled, the source calculates the file size before it starts mirroring. This can take a significant amount of time
depending on the number of files and system performance. Disabling calculation will result in the mirror status
not showing the percentage complete or the number of bytes remaining to be mirrored. A server setting, called
CalculateByVolume, is available through the Storage Mirroring text clients to workaround this limitation.
This setting will get the amount of disk space in use for the entire volume from the operating system, so the
calculation occurs instantaneously. However, if the entire volume is not being replicated, the mirror percentage
complete and bytes remaining will be incorrect accordingly. See the Scripting Guide for more information on
this server setting.