Dell PowerVault DP600 - Manual (Page 52)

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Component Default Allocation Location
• (Data source size x
retention range in days x
0.02) + 1600 MB
For system state:
• (Data source size x
retention range in days x
2) / 100 + 1600 MB
Change journal (for file
protection only)
300 MB Protected volume on the file
server or workstation
The values used in the preceding table are defined as follows:
• Alert%—Threshold for the alert associated with replica growth; typically 90%.
• Log change—This is the change rate on the database or storage group in question. This
varies widely, but for the purposes of the default recommendation in DPM, it is assumed to
be 6% for Exchange and SQL Server data and 10% for Windows SharePoint Services data.
• Retention range (RR)—This is the number of recovery points stored; it is assumed to be 5
for purposes of the DPM default recommendation.
• System state data source size—The data source size is assumed to be 1 GB.
When you create a protection group, in the Modify Disk Allocation dialog box, the Data Size
column for each data source displays a Calculate link. For the initial disk allocation, DPM applies
the default formulas to the size of the volume on which the data source is located. To apply the
formula to the actual size of the selected data source, click the Calculate link. DPM will
determine the size of the data source and recalculate the disk allocation for the recovery point
and replica volumes for that data source. This operation can take several minutes to perform.
We recommend that you accept the default space allocations unless you are certain that they do
not meet your needs. Overriding the default allocations can result in allocation of too little or too
much space.
Allocation of too little space for the recovery points can prevent DPM from storing enough
recovery points to meet your retention range objectives. Allocation of too much space wastes disk
capacity.
If, after you have created a protection group, you discover that you have allocated too little space
for a data source in the protection group, you can increase the allocations for the replica and
recovery point volumes for each data source.
If you discover that you have allocated too much space for the protection group, the only way to
decrease allocations for a data source is to remove the data source from the protection group,
delete the replica, and then add the data source back to the protection group with smaller
allocations.