Algorithm for Splitting Tasks During a Multi-Stream Restore Operation

For optimum multi-stream restore operations, the restore data (AFiles) is split into tasks based on an algorithm.

Additional Settings Used in the Algorithm

Algorithm for Splitting Tasks

Procedure

1. NumberofTasksPerAFile = nRestoreStreamStarvationFactor x NumberOfStreams.

2. Decision matrix:

   If	Returns	Then	NumberOfItemsPerTask is Equal to
   NumberofTasksPerAFile > nMaxRestoreTasksPerAFile	True	NumberofTasksPerAFile := nMaxRestoreTasksPerAFile	NumberOfItemsInAFile / NumberofTasksPerAFile

Example 1

Restore parameters:

NumberOfItemsInAFile = 20,000

NumberOfStreams = 5

Procedure

1. NumberofTasksPerAFile = nRestoreStreamStarvationFactor x NumberOfStreams = 2 x 5 = 10.

2. Decision matrix:

   If	Returns	Then	NumberOfItemsPerTask is Equal to
   10 > 4	True	10 := 4	20000/4= 5000

Result

NumberOfItemsPerTask = 5000

NumberofTasksPerAFile = 4

Example 2

Restore parameters:

NumberOfItemsInAFile = 20,000

NumberOfStreams = 2

Procedure

1. NumberofTasksPerAFile = nRestoreStreamStarvationFactor x NumberOfStreams = 2 x 2 = 4.

2. Decision matrix:

   If	Returns	Then	NumberOfItemsPerTask is Equal to
   4 > 4	False	NA	20000/4= 5000

Result

NumberOfItemsPerTask = 5000

NumberofTasksPerAFile = 4

Example 3

Restore parameters:

NumberOfItemsInAFile = 4

NumberOfStreams = 2

Procedure

1. NumberofTasksPerAFile = nRestoreStreamStarvationFactor x NumberOfStreams = 2 x 2 = 4.

2. Decision matrix:

   If	Returns	Then	NumberOfItemsPerTask is Equal to
   4 > 4	False	NA	4/4= 1

Result

NumberOfItemsPerTask = 1

NumberofTasksPerAFile = 4

Related Topics

Control the Minimum Number of Files Required for a Task