Re: [Dump-users] Re: st driver's buffer corrupting multivolume dumps

[<br...@ke...>]

On Sat, Jan 07, 2006 at 11:04:47AM -0500, Eric Jensen wrote:

> Thanks very much for posting this.  One request for clarification:
> 
> Do those options need to be cleared before *writing* the dump, or only
> when trying restore the dump?  I suspect the former, but wanted to
> check. 

Before writing.  I did the successful verify that way too, with
buffering and async write turned off (the same as during the dump), but
I'd imagine that on reads, the caching probably doesn't do any harm at
either setting and doesn't really matter.

> Also (and please forgive my ignorance of this topic), is there a
> straightforward way to see what options are set for the drive already?
> It wasn't obvious in the 'mt' man page.

I don't know a way to do that without changing anything, but I did 
notice that whenever *any* tape driver option is changed with 
stclearoptions type commands, the driver seems to very helpfully send 
the new current state of *all* of the options to syslog.  There's 
probably a way to achieve that without changing an option, but I don't 
know offhand.  Also, the defaults for all of the tape driver settings 
are in the man page for the 'st' driver, so if you haven't changed 
anything, that should tell you what everything should be starting at.

> Finally, I assume that these
> options would need to be set/cleared after each reboot, but not in
> between?

Yes, the settings seem to be persistent for as long as the system is
booted up.  The mt-st package includes a program called stinit which
gets run at boot time by an init script.  Stinit looks at
/etc/stinit.def for any sysadmin-supplied settings for any tape drives
you'd like to have autoconfigured at boot time, and uses them to set up
all your tape drives for you ('man stinit').

-- 
+ Brent A. Busby,   UNIX Systems Admin	 +   "It's like being	+
+ James Franck / Enrico Fermi Institute	 +    blindsided by a	+
+     The University of Chicago		 +    flying dwarf..."	+