T10000C - The Difference Between Native Sustained Data Rate and Full File Host Data Rate

Asset ID:	1-72-1538109.1
Update Date:	2017-08-08
Keywords:

Solution Type Problem Resolution Sure

Solution 1538109.1 : T10000C - The Difference Between Native Sustained Data Rate and Full File Host Data Rate

Applies to:

StorageTek T10000C Tape Drive - Version Not Applicable and later
Information in this document applies to any platform.

Symptoms

Do not understand the difference between Native sustained data rate (252 MB/s) and Full file host data rate (240 MB/s).

Can understand Full file host data rate but not sure how Native sustained data rate is measured? Should Full file host data rate be used for backup planning?

Changes

New installation.

Cause

Understanding performance on the tape drive.

Solution

The full file host data rate is measured by sending 5 TB of data (non compressible data) to the drive to fill the cartridge.

The native sustained rate is the maximum write performance (with non compressible data) the drive can achieve between two wraps. At each wrap the drive stop and restart to the other direction so you have some seconds at each wrap without writing activity.

The full file host data rate is the maximum performance you can obtain when you do multiple stops because of the wraps.

It is not easy for a server to send data at 252 MB/sec so if you do a calculation with 240 MB/sec you have to be sure that the server and all other Hardware components of the backup : disks, SAN, network, sofwtare catalog, HBAs, ... are capable of providing 240 MB/sec throughput. Perhaps better to use a lower number .

It is also important to note that other vendors do not typically state the full file number, they provide only the native sustained rate. This value does not include the time necessary to change directions. We believe we can perform this change in direction faster than some other vendors. We specify the native sustained rate because that is what is vendors such as IBM specify so this allows you to compare our speed with IBM. The full file number is more realistic for the customer however if you have competitors and you specify the lower number, the competitor may tell the customer that their drive is faster. This is not correct, if we are compared to the competitor then we should compare the same number.

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