Migration of data in server storage, identification
processes for data deduplication, reclamation, and expiration might
run concurrently with client store operations. Administrative tasks
such as administrative commands or SQL queries from administrative
clients can also run concurrently with client store operations. Server
operations and administrative tasks that run concurrently can increase
the active log space that is required.
For example, migration of files from the random-access (DISK) storage
pool to a sequential-access disk (FILE) storage pool uses approximately
110 bytes of log space for each file that is migrated. For example,
suppose that you have 300 backup-archive clients and each one of them
backs up 100,000 files every night. The files are initially stored
on DISK and then migrated to a FILE storage pool. To estimate the
amount of active log space that is required for the data migration,
use the following calculation. The number of clients in the calculation
represents the maximum number of client nodes that back up, archive,
or migrate files concurrently at any time.
300 clients x 100,000 files for each client x 110 bytes = 3.1 GB
Add
this value to the estimate for the size of the active log that calculated
for basic client store operations.