HP DDS2 and DDS3 backward compatibility
Stefan Viljoen
Excuse me, this may be a bit OT:
Are HP DDS3 4mm DAT tapes downward compatible with HP DD2 - written 4mm DAT
tapes?
I have a situation at work were we are upgrading servers (SCO Unix) to
DDS3-using primaries, with a planned weekly switchon of "retired" DDS2
equipped servers and a load-to-synchronize on the old systems.
All this falls apart if the DDS2 drives on the old systems cannot read the
DDS3 written 4mm tapes originating on the new systems.
Anybody encountered this before? Can a HP DDS3 read a HP DDS2 written tape?
Thanks!
Stefan Viljoen
--
Starwars Forever!!!
Andrey Vlasov
it should works at least according specification for HP drives. DDS3 should support DDS2/DDS1 tapes. It recognize tapes through holes in the bottom part of the tape and switch in according mode. In DDS1 mode - you can read tapes but not to write. Sometimes this can stop to work but it happen only if one of the drive misadjusted at hardware level and it require hadware repair. You can met problem on software level like diffrent block size but you can easy fix it by pointing which block size on the tape. You should use same software for reading as was used for writing and in this case you should not have a problem. Most problems happen by software incompatibility or hardware fault like heads have diffrent angle at write and read. But in last case send you new drive to manufacture for replacement. You can dig out all this information from HP website, just check for description on your DDS-3 drive.
Andrey
David C.
>
> Are HP DDS3 4mm DAT tapes downward compatible with HP DD2 - written
> 4mm DAT tapes?
>
> I have a situation at work were we are upgrading servers (SCO Unix) to
> DDS3-using primaries, with a planned weekly switchon of "retired" DDS2
> equipped servers and a load-to-synchronize on the old systems.
>
> All this falls apart if the DDS2 drives on the old systems cannot read
> the DDS3 written 4mm tapes originating on the new systems.
>
> Anybody encountered this before? Can a HP DDS3 read a HP DDS2 written
> tape?
It's not clear what you are trying to do here.
Do you want to use your old DDS-2 tapes in a DDS-3 drive? If so, it
should work fine. The DDS spec requires that high-density drives be
able to read and write lower-density media. A drive that does not
support this is not fully DDS compliant.
Or are you trying to use DDS-3 tapes in a DDS-2 drive? If so, it should
not work at all. The drive may even reject the tape as soon as you
insert it.
-- David
Juergen Pfann
>
> Hi!
>
> Excuse me, this may be a bit OT:
>
> tapes?
>
> I have a situation at work were we are upgrading servers (SCO Unix) to
> DDS3-using primaries, with a planned weekly switchon of "retired" DDS2
> equipped servers and a load-to-synchronize on the old systems.
>
> All this falls apart if the DDS2 drives on the old systems cannot read the
> DDS3 written 4mm tapes originating on the new systems.
>
> Anybody encountered this before? Can a HP DDS3 read a HP DDS2 written tape?
>
>
> Stefan Viljoen
>
You could omit the manufacturer's two letters in the subject of your
post
and your two questions above - that would not alter anything (YES, there
are DDS drives from other companies, too...).
I do have no problems whatsoever with read and write access to (read
carefully,
please) DDS 1 media written by our HP workstation' DDS 2 drive with my
private Intel PCs' Sony DDS 3 and Archive DDS 1 drives.
You get the idea ? The term "media recognition system" describes the
main
idea of DDS compatibility - the drives automatically switch to the
highest
density within the DDS "family" spec. that is supported by drive AND
media.
Thus, the greatest common denom. in the above case is DDS 1, forced by
the tape media. Would I use DDS 2 media instead, then my Archive DDS 1
couldn't read the media.
But the story isn't finished here ;-). When I only had the Archive DDS 1
as my first "real" (not floppy) streamer, I accidentally got a bunch of
DDS 2 media from a mail order comp. - and they were happily usable as if
they were DDS 1, so I decided not to exchange them. After having bought
the Sony DDS 3, I was able to re-format them (taking 3 hours each), so
these tapes can store 4 GB uncompressed again - as opposed to 2 GB
before !
Of course (you guessed it), these aren't readable again by the DDS 1
drive...
So, finally, as answer to your questions, I'd say : YES, you should be
able to exchange _DDS 2_ media (but not DDS 3, of course) between DDS 2
and DDS 3 drives, and each drive should be able to read what the other's
written.
I said "should" because there IS a small chance of HW incompatibility
left, for instance drive heads' de-adjustment, or HW compression
enabled on one drive and disabled on the other - but in theory, it's
supposed to work the way you want it.
Stefan Viljoen
David C. <sham...@usa.net> wrote in message
news:uhf8v8...@qqqq.invalid...
> "Stefan Viljoen" <ry...@intekom.co.za> writes:
> >
> > Are HP DDS3 4mm DAT tapes downward compatible with HP DD2 - written
> > 4mm DAT tapes?
> >
> > I have a situation at work were we are upgrading servers (SCO Unix) to
> > DDS3-using primaries, with a planned weekly switchon of "retired" DDS2
> > equipped servers and a load-to-synchronize on the old systems.
> >
> > All this falls apart if the DDS2 drives on the old systems cannot read
> > the DDS3 written 4mm tapes originating on the new systems.
> >
> > Anybody encountered this before? Can a HP DDS3 read a HP DDS2 written
> > tape?
>
The situation is this - we have two servers that are to be replaced. They
have DDS2 tape drives. They will be replaced with newer servers equipped
with DDS3 tape drives. What we want to do is to be able to save data on the
new server's DDS3 drive to a DDS tape, below the 2GB limit of the old DDS2
drives, and then use that tape from the new server to keep the old server
more or less synchronised with regard to possible hardware failure or
integration problems with the "new" server.
> Do you want to use your old DDS-2 tapes in a DDS-3 drive? If so, it
Yes.
> should work fine. The DDS spec requires that high-density drives be
> able to read and write lower-density media. A drive that does not
> support this is not fully DDS compliant.
Thanks!