Steve Richter wrote:
>
> Brad,
>
> Sounds like a great product.


I want to think so. LOL


> With the volume id and seqnbr that is supplied when you copy to and from
> tape, your device could be a file system onto itself.

Actually that is what it was evolving back into today. I
originally conceptualized a version of this as NLS/400 - near
line storage.

With commands opn the AS?400 like this

NLSNEW VOLID ('TAPE023')  create a new virtual tape file with
the unique id TAPE023 on the NLS server.
---then you do your normal INZTAP, SAVLIB, etc. you just treat
it like a regular tape drive, and when you want to release that
virtual volume, you unload it
NLSLOAD VOLID ('TAPE023') load that virtual volume from the NLS
collection. Just like loading a tape physically.
NLSDEL VOLID ('TAPE023') delete virtual volume
NLSWRTCD  VOLID ('TAPE023') write the selected virtual tape to
one or more CDS
NLSWRTDVD  VOLID ('TAPE023') write the selected virtual tape to
one or more DVDs

then various listing commands to list the volumes by vol id,
tape volumen name, expiration date, creation date, etc, with
wildcards

basically what I am thinking is a WRKNLS like a workoutq, only
it has virtual tape volumes on it.

I actually got the PC side of this working tonight, it only took
4 hours. (We already had most of the building blocks to it.)

Now I have to get the AS/400 side written.

> With access to data stored at an ip addr, you might be able to enable an
> unattended ptf and/or release upgrade.  ( no need to load the next volume )

cute but I would need so0me cooperation ffrom the elephant

> All devices on the system ( tape, display, printer ) can be varied on and
> off.  Will your tape emulator respond to the VRYCFG cmd ?

sure, it is a tape drive to the AS/400


> Will all types of save and restores be supported ?

anything you can do with a tape drive you can do with this,
ecxcept get the reels to spin back and forth like a James Bond
movie. I suppose I could put some Xmas lights on it.

>  Esp system type saves
> like SAVSYS and SAVSECDTA.

All I do is write tape blocks and file marks to disk and read
them back. Same unit would work on Unix, Mainframe, whatever.
(except I do look at the tape labels, I might have to adjust for
that.)

> When you restore the system after a crash you mount your SAVSYS tape on the
> tape drive and IPL the system from source D.  Will the TE ( tape emulator )
> support this operation ?

If you can restore from a 7208 you can restore from this (I
would guess that measn yes.)


> I question that the save will run any faster than it does to a real tape
> drive.  Save to save file does not run any faster than save to tape.  Have
> you seen actual faster save results ?

No I don't have an AS/400 big enough to drive it at speed, all I
have are little ones (S10, p02, old old b10s, etc.)

When you write to a savf your as/400 is doing a lot of other
things. My PC is not. The PC disk drive has a burst mode of
100MB a second. And I'm planning to have a BIG writebehind cache
- like a gigabyte or two

with AS/400 tape sacves, it is like this

think think think write wait for drive think think think write
wait for drive

with my ssytem it will be more like this

think think think wrt think think think wrt

Can the fastest AS/400 outrun it? maybe. I would think the
slowdown would be the SCSI connection to the AS/400.

Weo could support a couple fo them at once and look like two
tape drives.  All the PC stuff is very fast, and it gets faster
by the day.

> Have you reverse engineered the data stream format used on tape operations ?
> Or has IBM supplied it to you ?

No need to. it's just bytes in blocks, withe tape marks between
the files. (A little more structured than that, but you get the
idea.)

> Can you explain the format of the tape data stream ?

tapes do something simple. it writes blocks of data followed by
a filemark, and then a second filemark (two in a row) at the end
of tape.

When do two saves to a tape, it writes volume header (80 char)
filemark hdr1, hdr2 file labels (filemark) data block data block
etc to end of that file, then filemark, eof1 eof2 file labels,
then filemark, then repeat headers and data for sencond file,
ending with EOV1 80 chars, then two file marks.

unlabeled tapes don't have all those volume and file headers,
but they still ahve file marks. In order to add data to the end
of the tape, the save or copy program positions to after the
second ending filemark, then backs up two filemarks, then
rewrites the first file makr and then adds the file, then adds
two file marks.

All that postioning is very slow (and hard on the tape) and I
don't have to do any of it.

I create disk files that consist of a block type (data block or
file mark) and some other overhead stuff, data length, then
data.

very very simple, but the devil is in the details.

Brad Jensen
elstore.com
NL:S/400 - could you use an extra terabyte or three of online
backup space?

(PS it is actually up to 320GB+raid, but with compression it
will be a LOT larger.)


--
Brad Jensen brad@elstore.com
President
Electronic Storage Corporation Tulsa OK USA
918-664-7276

LaserVault Report Retrieval & Data Mining
www.Laservault.com

www.eufrates.com - Add distance learning to
your site with easy course preparation


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