8 May
2007
8 May
'07
12:44 p.m.
I always figure there's a lot less to go wrong in
a DLT cartridge than there
is with a hard disk
The flaw in this argument is the time it takes to make another copy, which needs
to be done at some point to migrate to newer media.
You will only know the DLT has failed when you try to read it again.
If you care about the data, it should be kept in a form that is easily replicated
and verified, and you should assume that any single copy of that data WILL become
corrupted or unreadable over time.
8 May
8 May
1:02 p.m.
Al Kossow wrote:
I'm not sure that it matters though, not while the hardware to read whatever
media is being used still survives in healthy numbers. With any type of media
there will come a point where for all intents and purposes it's obsolete, but
migration should happen before that point's reached.
DLT is pretty quick in my experience for the sorts of data sizes typically
found on home machines. Different matter entirely (generally) in the corporate
world, of course.
I always
figure there's a lot less to go wrong in a DLT cartridge
than there
is with a hard disk
The flaw in this argument is the time it takes to make another copy,
which needs to be done at some point to migrate to newer media. You will only know the DLT has failed when you try to
read it again.
Surely that's true of any backup media? (Well, the exception being backup
media where you *know* it's broken just by looking at it!).
1:48 p.m.
On 5/8/07, Jules Richardson <julesrichardsonuk at yahoo.co.uk> wrote:
DLT is pretty quick in my experience for the sorts of
data sizes typically
found on home machines. Different matter entirely (generally) in the corporate
world, of course.
Until we upgraded to Ultrium tapes (super-super DLT at about
200GB/cart for the ones we use), we used to blow two copies of our
telescope data to SDLT on a continuous basis... the primary data from
the main part of the telescope went on both tapes, and raw waveform
data went on only one tape. We filled about 175 tapes per year at
about 140GB (before compression) per tape (~ 75-80GB/day) for an
aggregate total above 24TB per year (rough estimates from memory).
That's for the old telescope. The new one isn't finished yet, but is
much larger.
If you recall the old saw about a station wagon full of magtapes (or a
747 full of CDs), I am able to talk about the bandwidth of an LC-130
with a load of SDLTs from personal experience. ;-)
-ethan
1:11 p.m.
New subject: Backups - was Re: 8mm data cartridges
--- Al Kossow <aek at bitsavers.org> wrote:
DLT is great, I use it a lot, and we also use it at
work. Very reliable from what I've seen, only time you
run into issues is with the drive itself, and really,
really worn out tapes. If possible, verify backups on
another tape drive, or at least verify them - I had
one tape drive that would seem to write just fine, and
never report any errors. But the tapes wouldn't read
back! A backup you can't read is, well, not backed up.
Then again, we don't use DLT as an archive - just for
daily backups. I have no idea how readable this
DLTTape IV cartridge will be in 20 years.
Burning DVD or CD's is nice and "archival" since you
can't overwrite them, but beware that some cheap media
isn't really good for more than a few years. Of
course, we've had discussions about media, longevity
and how critical it is to make backups many times
before... So backup often, backup in different ways,
verify backups and most importantly, actually backup!
And if you need to be sure the data will be around for
years to come, you need to keep it live - keep it on
newer media, newer hard drives, whatever.
If the data is _really_ crucial, consider punching it
into tape. Unlike cards, tape can't get dropped and
knocked out of order. It's slow to punch and read
though, so I simply rigged my TeleType to run at 19200
baud. Hold on, the chad box is on fire again...
-Ian
I always
figure there's a lot less to go wrong in
a DLT cartridge than there
is with a hard disk
The flaw in this argument is the time it takes to
make another copy, which needs
to be done at some point to migrate to newer media.
You will only know the DLT has failed when you try
to read it again. 
1:32 p.m.
New subject: Backups - was Re: 8mm data cartridges
----- Original Message -----
From: "Mr Ian Primus" <ian_primus at yahoo.com>
To: "General Discussion: On-Topic and Off-Topic Posts"
<cctalk at classiccmp.org>
Sent: Tuesday, May 08, 2007 1:11 PM
Subject: Backups - was Re: 8mm data cartridges
DLT is great, I use it a lot, and we also use it at
work. Very reliable from what I've seen, only time you
run into issues is with the drive itself, and really,
really worn out tapes. If possible, verify backups on
another tape drive, or at least verify them - I had
one tape drive that would seem to write just fine, and
never report any errors. But the tapes wouldn't read
back! A backup you can't read is, well, not backed up.
Then again, we don't use DLT as an archive - just for
daily backups. I have no idea how readable this
DLTTape IV cartridge will be in 20 years.
Burning DVD or CD's is nice and "archival" since you
can't overwrite them, but beware that some cheap media
isn't really good for more than a few years. Of
course, we've had discussions about media, longevity
and how critical it is to make backups many times
before... So backup often, backup in different ways,
verify backups and most importantly, actually backup!
And if you need to be sure the data will be around for
years to come, you need to keep it live - keep it on
newer media, newer hard drives, whatever.
If the data is _really_ crucial, consider punching it
into tape. Unlike cards, tape can't get dropped and
knocked out of order. It's slow to punch and read
though, so I simply rigged my TeleType to run at 19200
baud. Hold on, the chad box is on fire again...
-Ian
MO media seems to be made to last a long time, plus it has a hard outer case
to protect it (unlike DVD or CD recordable).
Honestly how much of the GBs of files on your hard drive is user generated
and irreplaceable and how much is just OS/App bloat along with internet
downloads?
TZ
2:01 p.m.
New subject: Backups - was Re: 8mm data cartridges
On 5/8/07, Teo Zenios <teoz at neo.rr.com> wrote:
Honestly how much of the GBs of files on your hard
drive is user generated
and irreplaceable and how much is just OS/App bloat along with internet
downloads?
Part of my gigs and gigs is digital photographs going back to 1996 of
places and buildings in Antarctica that aren't there any more. I
would consider that irreplaceable. I do have multiple copies on
multiple (types of) media.
-ethan
2:23 p.m.
New subject: Backups - was Re: 8mm data cartridges
Ethan Dicks wrote:
Indeed, I have a 2TB array here which is about 2/3 full, and contains no
application, game or OS binary code at all. There's some source code in
there and a couple of FTP mirrors, but most of it is data of various kinds.
Peace... Sridhar
Honestly how
much of the GBs of files on your hard drive is user
generated and irreplaceable and how much is just OS/App bloat along
with internet downloads?
Part of my gigs and gigs is digital photographs going back to 1996 of
places and buildings in Antarctica that aren't there any more. I
would consider that irreplaceable. I do have multiple copies on
multiple (types of) media.
3:48 p.m.
New subject: Backups - was Re: 8mm data cartridges
----- Original Message -----
From: "Sridhar Ayengar" <ploopster at gmail.com>
To: "General Discussion: On-Topic and Off-Topic Posts"
<cctalk at classiccmp.org>
Sent: Tuesday, May 08, 2007 2:23 PM
Subject: Re: Backups - was Re: 8mm data cartridges
Ethan Dicks wrote:
Indeed, I have a 2TB array here which is about 2/3 full, and contains no
application, game or OS binary code at all. There's some source code in
there and a couple of FTP mirrors, but most of it is data of various
kinds.
Honestly
how much of the GBs of files on your hard drive is user
generated and irreplaceable and how much is just OS/App bloat along
with internet downloads?
Part of my gigs and gigs is digital photographs going back to 1996 of
places and buildings in Antarctica that aren't there any more. I
would consider that irreplaceable. I do have multiple copies on
multiple (types of) media.
Peace... Sridhar
Well I would expect people here to have "data", but I would think most
people just have stuff they can download or rip again (music and movies). I
have a few GB of pictures taken with a digital camera that get backed up a
few ways (mirrored to another machine, MO, and DAT). But if you look at the
GBs of files on my main machine its mostly OS, Apps, drivers, and Games that
take up the space, not user created data.
5 p.m.
New subject: Backups - was Re: 8mm data cartridges
Teo Zenios wrote:
Well I would expect people here to have
"data", but I would think most
people just have stuff they can download or rip again (music and movies).
The 'net is pretty transient, though. I've been bitten by things disappearing
in the past where I hadn't archived them locally because I'd made the
assumption that "they'd always be there". Worse still, the bigger the data,
the less likely it is to stay around.
6:01 p.m.
New subject: Backups - was Re: 8mm data cartridges
On 08/05/07, Jules Richardson <julesrichardsonuk at yahoo.co.uk> wrote:
The 'net is pretty transient, though. I've
been bitten by things disappearing
in the past where I hadn't archived them locally because I'd made the
assumption that "they'd always be there". Worse still, the bigger the
data,
the less likely it is to stay around.
Being a pack-rat by nature, I've always tried to keep things I
download; my "downloads" folder, which is just software, drivers, etc,
things you might consider transient, is currently up to 25.2GB...
It's been handy when needing old versions of things..
I keep everything important on RAID 1 array, to avoid drive failure;
just upgraded to 2x500GB drives in a little NAS box. Backups against,
erm, "operator error" up to now were always been overnight
incrementals to another HDD (when on the previous FreeBSD server) .. I
still have to replicate that again now somehow on the new box - maybe
a third drive on the USB port, once I break into the (linux)
firmware..
7:31 p.m.
New subject: Backups - was Re: 8mm data cartridges
Rob <robert at irrelevant.com> wrote: On 08/05/07, Jules Richardson wrote:
The 'net is pretty transient, though. I've
been bitten by things disappearing
in the past where I hadn't archived them locally because I'd made the
assumption that "they'd always be there". Worse still, the bigger the
data,
the less likely it is to stay around.
Well my laptop had 10,000 files (mainly system related - Windows 2K) when I first got it.
Now it has around 40,000 files largely thanks to Windows Update and storing all the old
trash... err... updates.
My stuff consists largely of YouTube video's (about 1 Gigs worth), pictures, images,
software (which is about 500MB's worth).
I back up to CD-R's monthly (usually 1 for Progran files and another for video's
etc.). I do have most of my YouTube video's on the aforementioned USB flash stick (in
another thread), but it doesn't work too well. For some strange reason it doesn't
like certain colours... either that or some parts of it's flash memory are faulty :(
I would backup to DVD-R's, but my drive can only read DVD's and not write to them
:(
I would be tempted to get a 400GB/800GB harddrive from PC world, but I suspect these new
vertical harddrives won't last half as long as my CD-R's, as they will be more
affected by gravity, won;t they?
Regards,
Andrew B
aliensrcooluk at yahoo.co.uk
8:59 p.m.
New subject: Backups - was Re: 8mm data cartridges
On Tuesday 08 May 2007 15:48, Teo Zenios wrote:
Well I would expect people here to have
"data", but I would think most
people just have stuff they can download or rip again (music and movies).
That's still a nontrivial investment in time, though, and how do we recover
that?
--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, ?a critter that can
be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin
11:47 p.m.
New subject: Backups - was Re: 8mm data cartridges
----- Original Message -----
From: "Roy J. Tellason" <rtellason at verizon.net>
To: "General Discussion: On-Topic and Off-Topic Posts"
<cctalk at classiccmp.org>
Sent: Tuesday, May 08, 2007 8:59 PM
Subject: Re: Backups - was Re: 8mm data cartridges
On Tuesday 08 May 2007 15:48, Teo Zenios wrote:
> Well I would expect people here to have "data", but I would think most
> people just have stuff they can download or rip again (music and
movies).
That's still a nontrivial investment in time, though, and how do we
recover
that?
--
Well they just download a few TB of other junk they will never use :)
9:54 p.m.
New subject: Backups - was Re: 8mm data cartridges
Teo Zenios wrote:
MO media seems to be made to last a long time, plus it has a hard outer case
to protect it (unlike DVD or CD recordable).
Honestly how much of the GBs of files on your hard drive is user generated
and irreplaceable and how much is just OS/App bloat along with internet
downloads?
TZ
eh.. I don't have a wide range of experience with MO... but the one
drive I have
(650MB Sony, 300ish meg per side)... is that it doesn't last.
For reasons unknown I've lost two discs worth of data. tried in
multiple drives...
spin, init, eject... won't come ready... data... gone ! MO drives... on
a shelf.
Maybe newer ones are better... maybe these got to warm ? don't know...
Just my $0.02 on MO.
-- Curt
1:48 p.m.
New subject: Backups - was Re: 8mm data cartridges
Mr Ian Primus wrote:
If the data is _really_ crucial, consider punching it
into tape. Unlike cards, tape can't get dropped and
knocked out of order. It's slow to punch and read
though, so I simply rigged my TeleType to run at 19200
baud. Hold on, the chad box is on fire again...
10GB is a lot of punched tape. 8-)
Peace... Sridhar
2:21 p.m.
New subject: Backups - was Re: 8mm data cartridges
Sridhar Ayengar wrote:
Mr Ian Primus wrote:
Bah... change the shapes of the holes to represent different patterns... you
could easily quadruple storage capacity! :-)
If the data is _really_ crucial, consider
punching it
into tape. Unlike cards, tape can't get dropped and
knocked out of order. It's slow to punch and read
though, so I simply rigged my TeleType to run at 19200
baud. Hold on, the chad box is on fire again...
10GB is a lot of punched tape. 8-) 
5:25 a.m.
New subject: Backups - was Re: 8mm data cartridges
Jules Richardson wrote:
Sridhar Ayengar wrote:
Still I think DNA tops serial storage capacity.
Mr Ian Primus wrote:
Bah... change the shapes of the holes to represent different patterns...
you could easily quadruple storage capacity! :-)
If the data is _really_ crucial, consider
punching it
into tape. Unlike cards, tape can't get dropped and
knocked out of order. It's slow to punch and read
though, so I simply rigged my TeleType to run at 19200
baud. Hold on, the chad box is on fire again...
10GB is a lot of punched tape. 8-)
7:47 p.m.
New subject: Backups - was Re: 8mm data cartridges
On Tuesday 08 May 2007 13:48, Sridhar Ayengar wrote:
Mr Ian Primus wrote:
Probably is...
Last time I worked with punched tape was all the way back in 1978. I remember
various-sized stacks of the stuff for different programs, etc. Given the
typical fanfold stuff that was in common use, how much data would an inch or
so stack of it hold?
--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, ?a critter that can
be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin
If the data is _really_ crucial, consider
punching it
into tape. Unlike cards, tape can't get dropped and
knocked out of order. It's slow to punch and read
though, so I simply rigged my TeleType to run at 19200
baud. Hold on, the chad box is on fire again...
10GB is a lot of punched tape. 8-)
Peace... Sridhar 
6:32 p.m.
New subject: Backups - was Re: 8mm data cartridges
If the data is _really_ crucial, consider punching it
into tape. Unlike cards, tape can't get dropped and
knocked out of order. It's slow to punch and read
though, so I simply rigged my TeleType to run at 19200
baud. Hold on, the chad box is on fire again...
May I backup a TB of data on that? o:o)
1:39 p.m.
On Tuesday 08 May 2007 12:44, Al Kossow wrote:
I mostly agree here... but at some level of data storage, tape is much
more economical to use than hard disk.
Up until this year (that is to say, through December 31 or so of last
year ;) we have used DLT media for our archival storage system here at
work, starting in about '96. Keeping two copies of the data is really
essential, but even with the 50+TB of content that we had in the system
when we started migrating to our new one (from DLT-IV in a DLT7000
drive to LTO2 tape), we had very little data ever lost, and I don't
think any data that got lost could be credited to the tapes - mostly
just due to bugs, power failures, etc with our HSM system.
But again, we did have bad tapes on occasion (hint: avoid Imation tapes)
but they were few enough in number that we never had a big enough
problem to lose data on two tapes that had the same data. Still it
wasn't too bad, IMO, as some of our tapes had over 1000 tape-mounts,
with no problems at all.
So, I guess my advice if you want to use DLT tape (or newer, LTO stuff
which is starting to trickle down) is to make sure the tapes are in a
good, climate controlled environment, make sure you have 2 copies of
the data, make sure you clean and test the drives regularly,
occasionally read the tapes to make sure your data is still there, so
that you can regenerate a 2nd good copy before you have 2 bad copies.
Pat
--
Purdue University Research Computing --- http://www.rcac.purdue.edu/
The Computer Refuge --- http://computer-refuge.org
I always
figure there's a lot less to go wrong in a DLT cartridge
than there is with a hard disk
The flaw in this argument is the time it takes to make another copy,
which needs to be done at some point to migrate to newer media.
You will only know the DLT has failed when you try to read it again.
If you care about the data, it should be kept in a form that is
easily replicated and verified, and you should assume that any single
copy of that data WILL become corrupted or unreadable over time.
6279
days inactive
6280
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21 comments
13 participants
participants (13)
-
aek＠bitsavers.org -
alexandre-listas＠e-secure.com.br -
aliensrcooluk＠yahoo.co.uk -
bfranchuk＠jetnet.ab.ca -
ethan.dicks＠gmail.com -
ian_primus＠yahoo.com -
julesrichardsonuk＠yahoo.co.uk -
pat＠computer-refuge.org -
ploopster＠gmail.com -
rescue＠hawkmountain.net -
robert＠irrelevant.com -
rtellason＠verizon.net -
teoz＠neo.rr.com