Other Factors That Affect Job Speed - HP BB118BV - StorageWorks Data Protector Express Package User's Manual & Technical Reference

backup streams, thereby affecting the speed at which the job runs. Assigning the proper number of data
streams can help speed up the data transmission rate.
In general, you should assign data streams according to the number of streams the physical device (for
example, the disk drive) is capable of handling. Usually this number is equal to the number of spindles the
drive has. Under most circumstances, you should use this number to determine the number of data streams.
One exception to this general rule is when you are working with very large files. You can increase
performance by creating an additional stream for each of these very large files. For example, if you have
a very large file with 1.0 GB or more, create a separate stream for this file. Then Data Protector Express
will be able to send the file to the tape drive at a higher rate that allows for "streaming."
Consider these three examples:
1. A RAID device is capable of sustaining multiple data streams at once. By assigning various
directories on the RAID device to additional streams, you can increase the rate of data
transmission. To do so, assign large directories to their own streams by changing the Backup
stream field of each directory's Storage page to Create new stream. Don't add any more
streams than the RAID device can sustain.
2.
On the other hand, a single physical device may have multiple logical volumes. If each volume
is assigned a separate stream, this will not result in faster data transmission and may, in fact,
result in slower data transmission if it creates additional seeks by the disk drive. To turn off
one of the data streams, change the Backup stream field on the volume's Storage page to
Use existing stream.
3.
Some file or application servers may have large catalog files on them, perhaps 1.0 GB or larger.
These files should be assigned to their own streams. To do so, change the Backup stream field
on the file's Storage page to Create new stream.
In general, when creating or modifying data streams, first use the capacity of the physical device to
determine the optimum number of data streams and then create separate streams for very large files. Too
few or too many data streams will impede maximum performance.
You may experience problems with data streams if you have not dedicated any streams to specific
volumes or files. Problems may also occur if you exceed your hardware or operating system capacity.

Other factors that affect job speed

Additional factors that affect job speed include:
File compression
When a backup device compresses files, for example at a ratio of 2:1, a proportionately greater amount
of data needs to be sent to the backup device for it to stream. However, when files are sent across the
network already compressed, as NetWare does, further compression by the backup device will be
negligible.
NOTE:
Compression ratios vary among devices.
File encryption
run. When a machine has to use extra resources to encrypt files, a proportionately greater amount of
load is placed on the machine.
Minimize small file size
are small files. If you can limit the number of small files you back up, especially those smaller than
64K, your job will run more quickly.
CPU speed
when deciding where to place the backup device and to locate the catalog.
RAM In general, additional memory results in faster backups. By default, Data Protector Express
allocates 25% of physical memory, up to 32MB per device, for buffering. If you have four devices on one
Whether or not files are compressed by the backup unit affects how fast jobs run.
Depending on your hardware and the level or encryption selected affects how fast jobs
Large files transfer and are written to the backup device more efficiently than
In general, a faster CPU results in faster backups. Take the speed of the CPU into account
User's Guide and Technical Reference
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