Plesk 8.1 is able to do it. In community preview:
Usage: pleskbackup [<global-options>] <command> [<local-options>] <arguments>
<output-file>
Global options:
-v|--verbose
Show more information about backup process. Multiple -v
options increase verbosity.
-c|--configuration
Backup only configuration of objects, not the content.
-s|--split[=<size>]
Split the generated backups to the parts. Parts are numbered
by appending .NNN suffixes, starting with .001.
Size may be specified in kilobytes (<nn>K), megabytes (<nn>M)
and gigabytes (<nn>G).
'-s' option without argument selects default split size:
2 gigabytes.
-z|--no-gzip Do not compress backup file
Commands:
all Backs up whole Plesk.
clients Backs up selected clients. Clients are read from command line,
space-separated. If no clients provided, backs up all clients
on the host.
domains Backs up selected domains. Domains are read from command line,
space-separated. If no domains provided, backs up all domains
on the host.
Options --exclude and --exclude-file may be specified for
excluding some clients/domains.
help Shows this help page
Local options:
-f|--from-file=<file>
Read list of domains/clients from file, not from command line.
File should contain list of domains/clients one per line.
--exclude=<obj1>,<obj2>,...
Excludes listed domains/clients from backup list.
--exclude-file=<file>
Excludes domains/clients listed in file from backup list.
File should contain list of domains/clients one per line.
--skip-logs Do not save log files in the backup file
Output file:
Backup file. '-' means 'stdout'.