MAM Cartridge

STB Suite | The Industry Standard in Peripheral Testing.

Introduction

All LTO tape drives and tape cartridges incorporate a memory chip referred to as LTO-Cartridge Memory or “MAM” (Media Auxiliary Memory). This memory is inside each tape cartridge and is accessed wirelessly by the tape drive. The memory is partitioned into various sections, one of which is Tape Usage. The STB Suite has a function to retrieve and display this tape usage data. It is accessed via the STB Suite Original mode top menu Tape->Commands->Read LTO Cartridge Memory choice.

 

 

Cartridge Manufacturer Information

This section shows what company manufactured the tape cartridge, its serial number, cartridge type, date of manufacture, date the servo information was written, and which manufacturer wrote the servo information.

Initialization Data

This section shows what was the first drive used to initially write to the tape cartridge, and what format it was initially written in.

EOD Information

This area shows the number of filemarks and records on the cartridge, whether the EOD (End Of Data) mark on the tape is valid, and which wrap of the tape the EOD mark is written on.

Status & Alert Flags

This area shows the total thread count (Number of times the tape has been mounted by a drive) and any Tape Alert Flags which may be set.

Usage Pages

This section is broken up into four subgroups, one for each of the last four times the tape cartridge was mounted and used. Here you will see the manufacturer of the tape drive used and its serial number, the tread count for this drive, the total numbers of datasets written and read. Also of main interest is the number of Write Retries, Read Retries, Unrecovered Write and Read errors, and the number of suspended Write operations.

Suspended Write Errors

A suspended write happens when during a write operation the tape servo information is temporarily lost, in other words a servo error occurs. At this point the drive will to move down the tape looking for an area where it can properly decode the servo information, thus properly knowing where it is writing the data.

Fatal –

A “Fatal” suspended write means that the drive could not find any area of the tape where the servo information can be properly decoded and the write operation could not complete. This is a good indication that the servo information on the tape cartridge is damaged. Servo information cannot be recreated or rewritten, so a cartridge with these type of Fatal errors should be discarded.
The example shown above is an LTO-5 cartridge with many Fatal Suspended Write errors. This tape should not be trusted.

Here is an example of an LTO-4 cartridge with much better history

Summary

The LTO MAM data in each tape cartridge holds data that is very valuable when troubleshooting tape problems. The history of how the cartridge behaved during the last four mounts can show trends or problems either caused by a particular tape drive or problems within the tape cartridge.