You can tune the client to use less memory during incremental
backup operations.
Client memory requirements and ulimit settings for incremental backups
The amount of memory that is used for normal incremental
backups is proportional to the number of files that are being examined
for backup. When you start an incremental backup operation that backs
up numerous files, one way to prevent the client from running out
of usable memory is by setting the operating system ulimit data value
(ulimit -d) to unlimited.
Reduce client memory use
The memoryefficientbackup client option
determines how much memory the client uses during incremental backup
operations. Restricting the amount of memory that the client can use
during incremental backups reduces the efficiency of incremental backup
processing. The default setting for the memoryefficientbackup option
is no, which does not limit the memory that the client
can use.