Peter Mueller wrote:
Gene Heskett wrote:
Where are the old days, when ANSI tapes had these metal patches to
indicate BOT and EOT .... ;-)
Dunno, but FYI, the DDS tapes have about 1/16" diameter holes for
optical detection of BOT & EOT, about a foot back from the leader
splice on either end.
Yes, indeed! And those holes are checked to stop the tape from unwinding
from the spindle: the tape is not *fixed* to the spindle with glue or
something, the tape just winds around it, that's all. And it is stopped
unwinding just before it would come loose.
I saw that when it failed and ripped the tape in two on one drive back
in jurrasic times.
So who's throwing away the information ?
The tape drive not sensing these holes ?
The low level driver not recognising or not asking for the info ?
The general linux/unix tape system not recognising or asking for the info ?
I have the same question. But no answer.
I can only assure that my previous AIT-1 tapes only reported 4 times in
it's life time (it's dead now) an IO-error, while several other times,
it claimed "No space on device", not even near the end, while rewriting
the same tape a few days later could put much more data on it.
That tapedrive was connected to Linux but previously to a Solaris
machine, and both had the same view of IO-error versus 'No space on
device.' I even made a graph of it with gnuplot:
ftp://ftp.xplanation.com/xchange/20051216-20060317_JcFOLPUy/amanda-graph.gif
The horizontal axis is the run-number, the vertical axis is the amount
of bytes written to tape. (Yes it's the same graph, that I posted about
3 months ago.)
The red mark (IO error) around run number 2400 occured when the airco in
the computerroom was broken. The red mark near 2900 was when the tape
got stuck in the drive. I have no explanation for the red marks around
1500 or around 2000.
Around run 2200-2400 on the graph, the tape drive was switched from a
Solaris host to a Linux host.
Actually these are two tape drives operated with chg-multi. And both
showed the same phenomenon. One is still alive, the other one is death.
When I have more time, I'll try make the same graph for a pair of
DDS-2 tapedrives, that I used before the AIT-1. My current tapedrive,
an LTO-2, did not run into EOT (yet).
--
Paul Bijnens, Xplanation Tel +32 16 397.511
Technologielaan 21 bus 2, B-3001 Leuven, BELGIUM Fax +32 16 397.512
http://www.xplanation.com/ email: Paul.Bijnens AT xplanation DOT com
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* F6, quit, ZZ, :q, :q!, M-Z, ^X^C, logoff, logout, close, bye, /bye, *
* stop, end, F3, ~., ^]c, +++ ATH, disconnect, halt, abort, hangup, *
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