Oracle HSM: sam-arcopy Is Writing Data Below Native Data IO Rates With ssum Used (Doc ID 2127682.1)

Last updated on APRIL 19, 2016

Applies to:

Oracle Hierarchical Storage Manager (HSM) and StorageTek QFS Software - Version 5.0 and later
Information in this document applies to any platform.

Symptoms

Customer measured archiving performance and found that his T10000D drives performed well below their native I/O rates. He was expecting somewhere up to around 250MB/sec but found many sam-arcopies completing at or below 100MB/sec.

We could measure these times by dividing the time into the number of bytes written, as shown in entries like the following, found in the /var/opt/SUNWsamfs/devlog/[tape drive eq id] files.  The example below equates out to a roughly 100MB/sec arcopy:

It was also observed that with the Distributed I/O feature in use, the sam-arcopies handled by their QFS clients are much faster and can write at the data rates expected for their T10000D drives.

Cause

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