HP StoreOnce Backup System Concepts and Configuration Guidelines (BB877-90913, November 2013)

Maximum concurrently open files
The table in Key parameters (page 115) shows the maximum number of concurrently open files per
share and per StoreOnce appliance for files above and below the 24 MB dedupe threshold size.
A backup job may consist of several small metadata/control files (that are constantly being updated)
and at least one large data file. In some cases, backup applications will hold open more than one
large file. It is important not to exceed the maximum concurrent backup operations.
If these thresholds are breached the backup application will receive an error from the StoreOnce
appliance indicating that a file could not be opened and the backup will fail.
The number of concurrently open files in the table do not guarantee that the StoreOnce appliance
will perform optimally with this number of concurrent backups, nor do they take into account the
fact that host systems may report a file as having been closed before the actual close takes place,
this means that the limits provided in the table could be exceeded without realizing it.
Should the open file limit be exceeded an entry is made in the StoreOnce Event Log so the user
knows this has happened. Corrective action for this situation is to reduce the overall concurrent
backups that are happening and have caused too many files to be opened at once, maybe by
re-scheduling some of the backup jobs to take place at a different time.
Maximum number of NAS shares
The total number of “devices” provided by a StoreOnce appliance is split between VTL, NAS and
Catalyst devices..These devices may be all VTL, all NAS or any combination of NAS and VTL
devices. The following table illustrates some possible configurations.
Table 7 Maximum number of virtual devices per service set
Total number of devicesCatalystNASVTL
48 (maximum)0048
48 (maximum)0480
48 (maximum)4800
48 (maximum)02424
48 (maximum)0471
47 (less than maximum)0047
50 (more than maximum,
you will not be able to
create devices 49 and 50)
02030
36 (less than maximum)121212
48 (maximum)161616
12 (less than maximum)354
Maximum number of files per NAS share and appliance
The HP StoreOnce NAS implementation is optimized for use with backup applications. These
applications create large backup files on the NAS share, which make much more efficient use of
deduplication than simply copying files of various sizes to a deduplicating share. To improve
performance for small metadata files created by backup applications and to allow random access
to the header information at the beginning of backup files, the first 24 MB of any backed up file
will not be deduplicated. This non-deduplicated region is called the deduplication threshold.
The HP StoreOnce Backup System imposes a limit on the number of files that can be stored on
each NAS share. The limit is 25000 files, which provides the ability to protect a large amount of
data using a backup application. The limit is imposed in order to allow efficient use of data
replication.
Shares and deduplication stores 71