Q40 Tape Library
Installation and Operations Manual
511026 Rev. 07-01-19
146
8.4.1 Average File Size
The hard drive must seek to the position of a file before it can start reading. The more seeks a drive must
perform will lower the overall performance of the drive. Therefore, if the average file size is small, the
read performance will be slower.
To determine the average file size, divide the size of the backup by the number of files.
If the average file size is small (64 KB or less), consider using a sequential, image, or block backup
method that backs up the whole hard drive or LUN image instead of individual files. The tradeoff for using
one of these methods is that you might only be able to restore the entire image instead of individual files.
NOTE
File fragmentation will also cause excessive drive seeking, which lowers
performance, so ensure that files are regularly defragmented.
8.4.2 File Storage System
The file storage system determines the organization of the files on the disks. Using RAID controllers to
spread files over multiple disks can improve performance because some disks can be seeking while
others are reading. Storing files on a single non-RAID disk results in the slowest performance while
storing files on a high-end disk array results in the fastest performance.
Converting standalone disks to RAID can improve performance.
8.4.3 Connection from the Backup/Archive Host Server to the Disk Array
The connection between the host server and the disks determines how much data can be transferred
from the disks to the host computer at a time. A connection with insufficient bandwidth cannot provide
enough data for the tape drives to write at full speed. For optimum performance, the storage subsystem
must be able to provide data at the tape drive’s maximum transfer rate.
Backup systems using a lower speed Ethernet network should use multiple network connections.
8.4.4 Backup/Archive Server
The backup server must have enough RAM and processor power to transfer the files from the disk to the
tape drive, in addition to running the backup or archive software and any other processes.
Check the RAM and processor usage during a backup operation. If they are operating at capacity, adding
RAM or processor capability can improve performance.
8.4.5 Backup/Archive Software and Method
Each backup method has its own impact on performance, depending on how well it can keep data
streaming to the tape drive. In most cases, native applications don’t have the features required to
maximize performance for LTO tape drives. It is recommended to use a full-featured backup or archive
application with this library.
File-by-file backup or archive methods provide the best restore performance if you only need to restore
individual files. However, if the average file size is small, file-by-file methods will significantly reduce
performance.
Disk image, flash, or sequential backup methods provide the fastest performance because they back up
an entire disk, partition, or LUN, which minimizes disk seeking. The disadvantage is that backup and