Well, my server, just for my little operation here, has 8 GB of storage at
the moment, and I easily can fit that on a 112 meter 8mm tape costing about
$4. The EXB8505XL is capable of writing to tape at only 30 MB/min but can
accept data at around 20 MB/sec in synchronous mode and buffering it until
the buffer's full enough to warrant writing data to the tape. If data comes
over the (100 Mbps) net at a rate slower than the tape, it has enough buffer
memory to mask the start-stop time. However, there's quite a bit of
overhead and the buffer isn't deep enough to buffer backup and resync
operations followed by search for the appropriate record to start writing
where it left off. I went from standard coax to fast ethernet (TP) just to
make certain MY backups would happen over night.
My server's TEENSY by comparison with some people's. The
family-history-center at a friend's church has on the order of 200 GB of
data expanded over the course of several days' time from CD. If they lose
one of their drives, it's easier to restore from tape than to spend the time
redoing the expansion. That's why backups are preferable. They got an
EXABYTE tape library with two of Exabyte's fastest drives in it and a
capacity of 48 (?) 14.5GB tapes. NT doesn't handle libraries well with its
internal backup SW. It's probably because the driver used to integrate the
backup device into the system isn't comprehensive enough. They don't have
to run backups often, in fact, only after new material has been added to the
system. Expanding a 100 CD set takes lots of time and it should be
automatic from the tapes. I'm afraid to see what happens when they try it.
please see additional comments below.
Dick
----- Original Message -----
From: ajp166 <ajp166_at_bellatlantic.net>
To: <classiccmp_at_classiccmp.org>
Sent: Saturday, September 02, 2000 7:07 PM
Subject: Re: D'oh! Backup issue solved
> From: Richard Erlacher <richard_at_idcomm.com>
> >ANY Win9x-based utility that actually would provide a no-nonsense backup
> >procedure, one that would recognize that it formatted the tape, one that
> >would follow its own schedule and would recognize the same tape each
> time it
> >was in the drive. I'd like it to start within 1 minute of when it's
> invoked
> >when running on a 150 MHz machine, and that wouldn't ask me more than
> once
> >if REALLY want to do what I just typed. I'd like it to go ahead and
> back up
>
>
> Replica isn't too bad along those lines. ran is for a year on a P133
> (not mmx even!)
> off a AHA5142 on a HPt20 under NT3.51. The only thing it would not do is
> back up
> network drives.
>
> >open. When I'm using a 20-tape library, I'd prefer it NOT ask for
> >permission to use the next tape, and, having gotten that perimssion, I'd
> >prefer it not ask again before overwriting the tape. I'd prefer it be
> able
> >to read the backup it wrote yesterday, and I'd be happy if it could
> >recognize the tape it just formatted.
>
>
> I though of getting a Quantum DLT but the cost was high. The Replica
> software plays well with it though. It can be preset to overwrite if
> needed.
>
> >If you know of such a device that works with 4 or 8mm SCSI devices, 100
> >percent of the time, preferably unattended, and will actually utilize
> the
>
>
> Replica worked fine with my TLZ04 (4mm DDS1).
>
> >bandwidth of the tape device (80MB/sec, in bursts, 90 MB/min,
> >continuous/aggregate) please share the info with us. The NT stuff is
> the
>
>
> I have nothing to push tape that hard.
>
This doesn't push the tapes at all. The 85-90 MB/min isn't that fast. The
trick, however, is to keep the tape moving uniformly in one direction.
Ethernet, on its best day with a tailwind and a lightly loaded LAN will top
out (except in test situations) at about 10-12 Mbytes/minute. With highly
structured tests, it can do much better, but for random traffic, with
(mostly) only two stations loading the net, that's what I see very often.
The tape has to wait for the transfer, so it's got to start the tape moving,
find the append point, and go from there until the data runs out again.
Each time, it takes longer to move the tape than to transfer the data, yet
the data transfer is the rate-determining step. The computer's timing is
screwed up if there's any effort to synchronize, the tape drive's efforts
are wasted if the computer's behavior is constantly changing, and I haven't
a clue what the software does with all this, except that three out of four
attempts, no matter which Windows package is used, end in failure. I think
it's a flow-control problem that is brought about by the limited imagination
of the creators of the software. Sooner or later someone will bring it off.
>
> >only OS-resident software I've encountered that actually works. The
> backup
> >that comes with Win9x works with the picotapes that work on the floppy
> >ports, but they can't handle an adult's device.
>
> wrong tool.
>
It may be the wrong tool, but it makes all the claims suggesting it should
work. SInce the NT tool works so reasonably, I'm disappointed that the
Windows tools all seem to fall flat.
>
> >What really PISSES ME OFF about all this software, again, with the
> exception
> >of the NT stuff, is that it doesn't know about SCSI-1 devices, and
> doesn't
> >work one bit better on high-speed large-capacity disk drives than on
> tapes.
>
>
> W9x drivers are poor at best and ok only for desktop. NT is the only
> thing
> I'd consider other thn *nix for something server class.
>
Up to the time the motherboard I was using croaked, I had an NT box running
a mirror of my Netware server, with RAID-5 AND compression (more to increase
performance than capacity) as well as the pretty faithful emulation of the
Netware interface so I could talk to it from DOS and Win31x without having
to load the inordinately large drivers that go with ethernet interface code
other than what comes with Netware (and that's plenty big enough). The NT
package looks to the DOS stations like a normal Netware server. Whereas I
managed to get that part of the setup to work, I hadn't yet managed to get
the "easy" part, the Win9x <=> NT interface to work. I figure I can phase
out the old Netware if I can get this setup to come to life again.
>
> >backups of the whole system over the LAN every day, assuming there's
> enough
> >bandwidth on its 100Mb channel, I'd use it. I've bought a half dozen
> >different vendors' offerings, and half of them don't even run, let alone
> >perform backups.
>
>
> I don't like lan backup as they suck up all the bandwidth and leave the
> 'net useless for their run time. A 100mb channel is only good for maybe
> 20mb/s
>
Statistical access LANs are like that. What's more, there's plenty of
overhead. With the degenerate case, i.e. only two stations sending lots of
data and the remainder mostly quiet, you can get appreciably more, though
not as much as I'd like. I only have four stations operating these days,
and often two are asleep. It's no trouble doing the backup, yet it takes
most of the night. With standard ethernet, even under DOS when I could use
the really GOOD software that worked EVERY TIME, I couldn't transfer and
record the whole server every night, because it took more than the whole
night to do it. With all the drives on the network, it takes more than 24
hours to do the daily "full" backup. Incrementals suck, so I don't use
them.
>
> and even then I'd only expect half that, thats SCSI-1 perfomance at best.
>
> I havent tried a lot of packages, done have a lot of $$$ to spread so
> anything
> free or supplied with hardware is always tried. Replica came with the
> HPt20
> and worked with a lot of hardware I tried fairly well. However it's not
> the
> firebreathing stuff you use nor have I tried it at that level. For me a
> 3-5gb
> backup every night is easily handled with that and it runs during the
> night
> when our net is not in use.
>
> Allison
>
>
Received on Sat Sep 02 2000 - 21:46:43 BST