(I've been working on this issue for several years. The industry has not
been overly cooperative and I thank HPE for finally admitting issues)
If you have MAXELL LTO media, you should discontinue use of it ASAP.
(NB: MAXELL no longer produce LTO media of any kind and stopped doing so
about 2 years ago.)
IMPORTANT: MAXELL media may be present in virtually any brand of LTO
Ultrium cartridge (see below)
There are 2 reasons for this warning:
1: Excessive head wear
MAXELL LTO media is extremely abrasive - outside LTO specs - and use of
it results in head wear well beyond what is considered normal for LTO
drives (HPE refer to it as "pole tip recession")
This excess wear leads to degradation of write/read speeds along with
numerous rewrites of data and eventually the drive will become unusable
long before it should be.
2: Destruction of drives
Based on our tests and experience, MAXELL LTO media may destroy your
drive's read/write heads. The risk is significantly higher if you have
an IBM LTO drive.
Some LTO tapes with MAXELL media have an unknown serious issue which
results in total failure of the drive heads. This may occur at any point
in the tape but commonly happens about 3/4 of the way in.
I suspect this is related to a faulty servo track on the tape (there
are 4), but without openness from MAXELL and the LTO industry, it
remains only a suspicion.
WARNING: Because the issue usually only manifests once the tape has a
large amount of data on it, that tape may appear "normal" although not
holding as much data as it should (on LTO5 it usually occurs around
1100GB into the tape for non-compressible data) . The _next_ tape put
into the drive will fail completely and if you blame that one for the
failure, you'll never solve the problem.
This catastrophic damage happens on HP LTO drives with about 1 in 300
LTO cartridges containing MAXELL media.
It occurs on IBM LTO drives with about 1 in 20-50 LTO cartridges
containing MAXELL media.
(We originally suspected heavy tape contamination ex-factory and that
the damage then passed onto the next tape, but neither suspicion has
proven to be correct.)
IMPORTANT:
1: Faulty MAXELL media may test fine in HP drives, but still destroy IBM
drives. I know, because I've seen it happen - repeatedly.
2: Attempting to read a faulty tape will result in tape head destruction
too.
3: No amount of drive head cleaning or tape media cleaning will prevent
this occurring or prevent recurrences.
4: MAXELL media may be present inside virtually any brand of cartridge.
Whilst it is possible to work out if the media pancake inside a
cartridge could be MAXELL based on its serial number, the only reliable
way to verify the manufacturer of the actual media is to read the tape's
internal RFID chip. This contains details of both the OEM/OEM serial
number and the media manufacturer/pancake serial number.
External readers such as Veritape units can read the chip without
inserting the cartridge into a drive, otherwise the procedure for
checking this information is:
1: Insert the cartridge into the drive. DO NOT FORWARD SPACE.
2: If your system has the sg_read_attr command (sg3_utils 1.42 or
later), then use the following command:
# sg_read_attr /dev/{drive}
you will get a readout of the user-facing parts of the onboard chip.
at "Vendor specific medium attribute 0x1000: ", in the first line's
ascii decode section you will see some garbage output ending with "MAXE"
in cleartext and on the next line "LL ........" (Or
"SONY"/"TDK"/"FUJI"/others - manufacturer info is contained in bytes
12-19 of this attribute.)
3: If you don't have sg_read_attr (or would like to see the decoded
results of 0x1000), then follow this procedure:
3.1: Identify the generic device (/dev/sgX) of your drive
3.2: /usr/bin/sg_raw -o - -r 1024 -t 60 -v {/dev/sgX} 8c 00 00 00 00
00 00 00 00 00 00 00 04 00 00 00 > /tmp/ltomam
(If you have sg_read_attr, then sg_read_attr -r {DEVICE} >
/tmp/ltomam)
3.3: read the file using the modified (extended) version of Robin
Johnson's "read_attribute.pl " script I have provided at:
http://www.mssl.ucl.ac.uk/~ajb2/LTO/
This script is heavily commented and if anyone wants to make it better,
please do so.
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