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Re: Setting volume size for dump



Claus-Justus Heine wrote:
> 
> "Jens B. Jorgensen" <jjorgens@bdsinc.com> writes:
> 
> > Claus-Justus Heine wrote:
> > >
> > > > > Aren't these marks simply "file marks"? (just asking, I know that
> > > > > there are thos MTFSS/BSS/WSM tape operations, are these effectively
> > > > > different from the MTFSF/BSF/WEOF operations?)
> > > >
> > > > Yeah, it's a different beast. Trust, me, I can tell mt to find a mark
> > > > and it'll
> > > > skip over all kinds of file marks.
> > >
> > > So does this mean that "SETMARKS" are kind of "second level" file
> > > marks? I'm just curious what these things are. There is no real need
> > > for me to know it, I'm just curious.
> > >
> >
> > I'm not sure how they're physically done. I didn't even know of them
> > until I started I started writing my backup script. I just saw this
> > from the mt man page on our HPUX box:
> >
> >            smk       Write count setmarks (DDS drives only).
> >
> >            fss       Forward space count setmarks (DDS drives only).
> >
> >            bss       Backward space count setmarks (DDS drives only).
> 
> Mmmh. This suggests that these are just anotehr kind of file marks?
> 
>         weof    Write count file marks
> 
>         fsf     Forward space count file marks
> 
>         bsf     Backward space count file marks
> 
> Mmh ???
> 
> Again. I'm just curious.

I guess what you're asking is more than I know. How are these "marks" actually
represented on the media? I have no idea. They certainly are different than
file marks because when you search for a set mark you don't stop on a file
mark. I can also tell you that searching for a set mark is *much* faster than
searching for a file mark. I can't offer any hard numbers to back this up,
I've just found it to be true. This fact suggests to me that set marks are
fundamentally different than file marks.

Why don't you scour the web for for in-depth information? I'd really like
for you to email me the URL for such information if you find it since I, too,
am curious.

-- 
Jens B. Jorgensen
jjorgens@bdsinc.com


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