Sam,
Thanks for your reply...
Is there a way you tell if your drive is streaming? Or are you just
saying you do the best you can and hope it is streaming?
Best,
Dick
> > It is my understanding that this drive was delivered with HW compression
> > enabled. I have done nothing to disable it.
> >
> > After visiting their web site I see the problem...
> >
> > The tape is a V17. I did not recall, so I simply assumed that when you
> > mentioned the V10, that it must have been the correct number.
> >
> > The definition should then read:
> >
> > define tapetype V17 {
> > comment "V17 in ECRIX Model: VXA-1 Rev: 2959 w/HW compression"
> > length 55000 mbytes
> > filemark 1931 kbytes
> > speed 2024 kps
> > }
> >
> > Given this, Ecrix significantly overstates their capacity. For the V17,
> > they advertise 33G uncompressed and I got 27.5G. That's almost 17%
> > overstated.
> >
>
> The number you're stating is what tapetype gave you. I haven't looked at
> it, but I assume its calculations deduct inter-record gaps and associated
> overhead that it'd expect to incur when writing in normal "amanda use". As
> such the capacity figure will be less than the figure Ecrix states which is
> (probably) for one infinite length record. Whether or not 17% overhead is
> correct I can't say.
>
> > Is this common in the industry or is Ecrix out on a limb?
> >
> > Or am I misunderstanding the meaning of the numbers reported by
> > tapetype?
> >
>
> Either you or me (or maybe both of us :-)). Usenix has been using an
> autoPAK w/ V10 tapes for a while but I never had the time to let tapetype
> run to completion to get an "accurate" entry. Instead I use a hack:
>
> define tapetype VXA-V10 {
> comment "VXA-1 V10 Cartridge (107 meters)"
> length 20 gbytes # 40 GB with 2:1 compression
> filemark 100 kbytes # pure guess
> speed 3 mbytes # documented sustained transfer rate
> }
>
> and let amanda recover when it runs off the tape during multi-tape backups.
> That's why your posting caught my eye; I thought I'd be able to drop your
> entry in and eliminate this excess work.
>
> > > FWIW I run w/o h/w compression; my Dell 2450 host is way faster at doing
> > > gzip and I want the drive to stream whenever possible.
> >
> > Are you saying the drive does not stream with HW compression? How does
> > one know when the drive is streaming and when it isn't?
> >
>
> No. I'm simply saying that I take no chances that the drive may not stream
> by adding to the overhead of the controller. I assume the hardware is
> designed to stream even with h/w compression but I've had experience with
> some devices that slowed when doing compression. Besides, since gzip
> compression tends to be as good or better than any hardware compression I
> see no point in using h/w compression.
>
> Oh, and you asked about my OS and how I disable hardware compression. I use
> FreeBSD (4.3-RELEASE) and hardware compression is enabled or disabled by the
> driver.
>
> > Thanks,
> > Dick
> >
> > P.S. Please reply to: [EMAIL PROTECTED]
> >
> > > BTW, was this really with h/w compression enabled? You state 26.86G of
> > > writable space but the V10 cartridges are spec'd at 40G with
> compression.
> > > I'm curious because I have the same setup but never ran tapetype to
> figure
> > > out the actual capacity.
> > >
> > > FWIW I run w/o h/w compression; my Dell 2450 host is way faster at doing
> > > gzip and I want the drive to stream whenever possible.
> > >
> > > Sam
> > >
> > > ----- Original Message -----
> > > From: <[EMAIL PROTECTED]>
> > > To: <[EMAIL PROTECTED]>
> > > Cc: <[EMAIL PROTECTED]>
> > > Sent: Friday, January 18, 2002 3:56 PM
> > > Subject: Re: tapetype entries
> > >
> > >
> > > > You're right. I wasn't thinking... I guess it should be:
> > > >
> > > > define tapetype V10 {
> > > > comment "V10 in ECRIX Model: VXA-1 Rev: 2959 w/HW compression"
> > > > length 55000 mbytes
> > > > filemark 1931 kbytes
> > > > speed 2024 kps
> > > > }
> > > >
> > > >
> > > > > > define tapetype vxa1 {
> > > > > > comment "ECRIX Model: VXA-1 Rev: 2959"
> > > > > > length 27513 mbytes
> > > > > > filemark 1931 kbytes
> > > > > > speed 2024 kps
> > > > > > }
> > > > > >
> > > > >
> > > > > The VXA-1 is a drive. This is specific to a cartridge; e.g. V10.
> > > > >
> > > > > Sam
> > > > >
> > > > >
> > > >
> > > >
> > >
> >
> >
>
