| Author |
Message |
Nico de Jong
Guest
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 Posted:
Thu Sep 22, 2005 9:30 pm Post subject:
Re: DLT or LTO or AIT for new tape drive? |
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"Rob Turk" <_wipe_me_r.turk@chello.nl> skrev i en meddelelse
news:OpAYe.27$as3.9@amstwist00...
| Quote: | "Joe Rom King" <joeromking@yahoo.com> wrote in message
news:1127389914.639187.237500@g43g2000cwa.googlegroups.com...
Jeremey
Here is the citation: The Gartner Group reports that 40 to 50% of all
backups are not recoverable in full, and that 60% of all backups fail
in general3.
If 60% of all backups fail, this means only 40 % of all backups are OK.
If 40% to 50% of all backups are not fully recoverable, then 50% to 60%
of
all backups are.
Care to explain how you can get 50% to 60% good restores from only 40%
good
backups???
There's lies, damn lies and statistics.
Rob
The way I see it, there must be something fishy about either the restore |
program or the file system on the system to be restored to.
I've been working with streamers of various kinds since 1986 or so, and my
experience is that tape drives seldomly fail (well, apart from DDS)
I have quite some customers reading /writing tapes very often, so it
cannot
be a general tape-related or drive-related problem. My guess is that the
receiving system prevents the restore of various files, resulting in
unuseable "restored" systems
Nico |
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Rob Turk
Guest
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| Posted:
Thu Sep 22, 2005 10:46 pm Post subject:
Re: DLT or LTO or AIT for new tape drive? |
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"Nico de Jong" <first_name@FARUMDATA.DK> wrote in message
news:8ZAYe.259$7i6.11@news.get2net.dk...
| Quote: | "Rob Turk" <_wipe_me_r.turk@chello.nl> skrev i en meddelelse
news:OpAYe.27$as3.9@amstwist00...
"Joe Rom King" <joeromking@yahoo.com> wrote in message
news:1127389914.639187.237500@g43g2000cwa.googlegroups.com...
Jeremey
Here is the citation: The Gartner Group reports that 40 to 50% of all
backups are not recoverable in full, and that 60% of all backups fail
in general3.
If 60% of all backups fail, this means only 40 % of all backups are OK.
If 40% to 50% of all backups are not fully recoverable, then 50% to 60%
of
all backups are.
Care to explain how you can get 50% to 60% good restores from only 40%
good
backups???
There's lies, damn lies and statistics.
Rob
The way I see it, there must be something fishy about either the restore
program or the file system on the system to be restored to.
I've been working with streamers of various kinds since 1986 or so, and my
experience is that tape drives seldomly fail (well, apart from DDS)
I have quite some customers reading /writing tapes very often, so it
cannot
be a general tape-related or drive-related problem. My guess is that the
receiving system prevents the restore of various files, resulting in
unuseable "restored" systems
Nico
|
Agreed, many of the so-called 'failures' will probably be due to wrong
selection sets or operator error. The number of 'failures' increases
dramatically if no open file software was used and all reports of incomplete
backups due to locked files were added to the 'failed' category.
My point in the case above however, was that the math doesn't add up. It
claims that they were able to do complete and successful restores from about
20% of 'failed' backups. Smells fishy indeed..
Rob |
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Rod Speed
Guest
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| Posted:
Thu Sep 22, 2005 11:23 pm Post subject:
Re: DLT or LTO or AIT for new tape drive? |
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Joe Rom King <joeromking@yahoo.com> wrote
| Quote: | Jeremey
It sounds interesting - although "40% of
tape restores fail" is obviously wrong.
Here is the citation: The Gartner Group reports that
40 to 50% of all backups are not recoverable in full,
and that 60% of all backups fail in general.
|
Just numbers plucked out of someone's arse without
a shred of rigorous science to substantiate them.
And fuck all use tape outside large enterprises now anyway.
| Quote: | Even in large enterprise data centers, nearly one quarter of respondents
report that 20% or more of their tape-based recoveries fail."
|
Nothing like your original claim.
| Quote: | Source:http://www.exabyte.com/support/online/documentation/whitepapers/affordabletapeautomation.pdf
Are you just saving data or do you get registry backups as well?
This is predominantly a file-based backup. However it does
automate the System State backup, so yes registry, important
boot files, as well as Active Directory data can be backed up.
Are backups interchangeable between different systems?
If I understand your question, so yes the backup is portable.
That means if you loose one computer you can take the disk
to another computer, launch the Recover Settings wizard,
and then you can recover you entire data, or just selected
files/folders from any point in time you choose. |
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Rod Speed
Guest
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| Posted:
Thu Sep 22, 2005 11:27 pm Post subject:
Re: DLT or LTO or AIT for new tape drive? |
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Joe Rom King <joeromking@yahoo.com> wrote
| Quote: | Dear Arno
You have to agree with Gartner that at least 40% of tape restore fails.
|
No we dont, its a number plucked out of someone's arse.
| Quote: | Yes, it is true that you can improve on this number,
but you can do the same for disk. I just hope you and
others can look at this matter in a non-biased way.
|
Heard the one about hope springs eternal ?
| Quote: | P.S
I think that the correct capitalization of
'German' is more straightforward. |
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J. Clarke
Guest
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| Posted:
Mon Sep 26, 2005 7:26 am Post subject:
Re: DLT or LTO or AIT for new tape drive? |
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Joe Rom King wrote:
| Quote: | Perce
Tape has its own vulnerabilities:
Humidity will ruin any tape. Placing the tape near an electromagnet
source such as generator or a big electric engine are great ways to
implement a "secure delete". Placing the tape is a closed car in
the summer time, is another dead end road for tapes. Tapes are
vulnerable to wear and tear, about 30-50 cycles before they die on you.
|
DLT was tested to 500,000 cycles and was found to still be _improving_ at
that point. If your experience has been with Travan and DDS don't assume
that they are typical.
| Quote: | I know a customer that lost all of his data because his tape drive was
near a copy machine causing the toner particles in the air to make all
of his tapes unreadable.
Try shuttling a tape drive while it writes to tapes, especially if you
tilt them in a way that causes radial forces, and the tape will be
KPUT.
|
"Shuttling"? Would you care to define that term?
| Quote: | Statistics shows that 40%-60% of tape restores fails. Validating the
backed up data on tapes are very hard, sentencing your organization to
a life at the foothill of an active volcano.
|
It's not any more difficult than any other media--read the tape and compare
the contents to what is on the disk.
| Quote: | Disk is vulnerable to sever drop (can be easily solved with a cushioned
transport packaging), but is mostly immune to all above mentioned items
because of the hermetically sealed environment it operates in (dirt and
electromagnetic wise).
|
Disk are not hermetically sealed, and I would not be surprised at all if
toner would make it through the filter. There is no particular magnetic
shielding on disks--equidistant from a large magnet disk and tape should be
affected about the same.
| Quote: | The logical conclusion is not to rely on a single backup media, be it
tape or disk.
|
In this you are correct if the requirement is truly mission-critical.
| Quote: | Now for your question regarding generations and number of media:
Relative Rev Backup has a unique management algorithm that makes sure
you can have many months worth of backup generations stored on each
backup disk. However, if you have at least two backup disks in daily
rotation, any damage to any disk will result in loosing the backup of
the last day only. (Same effect as damaging the last tape).
That is what I mean by robust and cost effective at the same time.
|
For a small system using disks as removable media can be cost effective, but
regardless of the kind of software you're using you should use the same
multiple-generation with offsite storage strategy that you would use with
tape.
| Quote: | Joe Rom King
---
Http://www.datamills.com
Unattended File-Level Incremental Backup to Disk, with Backup
Generation Manager.
|
--
--John
to email, dial "usenet" and validate
(was jclarke at eye bee em dot net) |
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J. Clarke
Guest
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| Posted:
Mon Sep 26, 2005 7:26 am Post subject:
Re: DLT or LTO or AIT for new tape drive? |
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Lady Margaret Thatcher wrote:
| Quote: | I have a home LAN with about 20 GB online. As I get more into digital
photography and possibly even videos, I expect that amount of storage
can grow quite a lot in the next few years.
My current tape drive is 7/14 GB, and a full backup each month
requires about 4-5 media changes, counting the verify cycle. I would
like to get a drive that allows me to fit say 40 GB (or more) onto one
cartridge. Without bankrupting my Treasury of course.
Should I focus on DLT or AIT or LTO? 68-pin SCSI or even SCA.
|
All of them work--personally I'd lean toward LTO--the tapes are getting to
be very reasonable for the amount of storage they hold, although the drives
are still expensive.
You're pretty much limited to SCSI, and go 68-pin--SCA is only an advantage
for hot-swapping the drive, otherwise it's a liability because if you don't
have a backplane you have to use an adapter and the adapters I've seen are
all pretty clumsy.
| Quote: | Which format is most reliable and cost-effective, considering both
drive and media cost? What about buying a drive used on eBay? (no
flames please!) Are any of these formats dead-ends like my current 8
mm drive/format?
|
You can often find bargains in used DLT drives on ebay--the drives are
pretty durable and companies needing more capacity will often surplus out
lower-capacity drives that are in good working order.
| Quote: | I don't need to back up 20 GB in say 30 minutes. I doubt my systems
could even pump out the data fast enough.
|
That's not really all that high a data transfer rate these days.
| Quote: | (I'm moving to 1 GB LAN for
my newer systems.) A drive with say 40-80 GB native storage would
give me enough "headroom" so that even 2-4 years from now, I should
still be able to do a full backup with one cartridge.
Also, do any of these formats "shoeshine" the tape if the drive isn't
getting data fast enough?
|
Not really any other way do deal with the situation.
--
--John
to email, dial "usenet" and validate
(was jclarke at eye bee em dot net) |
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Curious George
Guest
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| Posted:
Wed Oct 05, 2005 11:33 pm Post subject:
Re: DLT or LTO or AIT for new tape drive? |
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|
On Wed, 14 Sep 2005 21:56:34 -0700, Lady Margaret Thatcher
<Was_at_10_Downing_Street@bad_for_the_UK.org> wrote:
| Quote: | On Tue, 13 Sep 2005 18:50:06 +0200, "Rob Turk"
_wipe_me_r.turk@chello.nl> wrote:
"Lady Margaret Thatcher" <Was_at_10_Downing_Street@bad_for_the_UK.org> wrote
in message news:ourci11bug3qcc1fqjb1bfjk6rtm43p051@4ax.com...
I have a home LAN with about 20 GB online. As I get more into digital
photography and possibly even videos, I expect that amount of storage
can grow quite a lot in the next few years.
My current tape drive is 7/14 GB, and a full backup each month
requires about 4-5 media changes, counting the verify cycle. I would
like to get a drive that allows me to fit say 40 GB (or more) onto one
cartridge. Without bankrupting my Treasury of course.
Should I focus on DLT or AIT or LTO? 68-pin SCSI or even SCA.
Which format is most reliable and cost-effective, considering both
drive and media cost? What about buying a drive used on eBay? (no
flames please!) Are any of these formats dead-ends like my current 8
mm drive/format?
How about VXA-2 from Exabyte? Cheap drives, very reliable technology. By
|
but the tapes are a little pricey so it's not the bargain it may first
appear.
| Quote: | Well, nothing against Exabyte, but their drives and media, while good,
aren't as bullet-proof, never-fail as my earlier QIC drives, including
a 1 GB native Tandberg drive. But that format seemed to becoming
obsolete, and newer drives couldn't even read some of the older QIC
formats.
|
compatibility was one issue with QIC. The other is that
"bullet-proof, never-fail" was not typically used to describe them.
| Quote: | I would like to avoid that scenario again.
using the short X6 tapes you can get the capacity you need today at a very
good price, and if you need more capacity you can go to X10 or X23 tapes for
more.
Sounds good. I'll have to check it out. Which vendor is preferred?
Or to be avoided.
All media formats are dead-end at some point. DDS is dead-end today.Your
current 8mm drive format has been around for 25 years before becoming
obsolete. DLT is about to become extinct. LTO is master of the enterprise
Ah. I hadn't realized that DLT is dead-ending.
|
It isn't really. SDLT replaces DLT but some backwards-compatability
remains. There are so many DLT systems in service that there should
be no problems coming by tapes & parts for the next few years (which
is all you should expect anyway).
| Quote: | LTO might be nice.
If it is master of the enterprise, that tells me it's reliable. But
it also tells me that it could be too expensive for me, and the native
transfer rates to keep an LTO drive "full" might be more than my LAN
could possibly supply.
I previous asked about "shoeshining" with different formats. Is AIT
less prone to shoeshining than the other formats?
|
That's software & configuration specific except for some LTO's that
can adjust speed to compensate.
| Quote: |
universe today, but real overkill for your application.
Yes, could be. Heck none of my systems are even rack-mounted, and
every self-respecting enterprise I know about is all "how many U is
that server, " and about blade servers to increase CPU density per
rack.
Thanks for your reply.
Thatcher |
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Nico de Jong
Guest
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| Posted:
Thu Oct 06, 2005 12:07 am Post subject:
Re: DLT or LTO or AIT for new tape drive? |
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| Quote: | Well, nothing against Exabyte, but their drives and media, while good,
aren't as bullet-proof, never-fail as my earlier QIC drives, including
a 1 GB native Tandberg drive. But that format seemed to becoming
obsolete, and newer drives couldn't even read some of the older QIC
formats.
compatibility was one issue with QIC. The other is that
"bullet-proof, never-fail" was not typically used to describe them.
In my +20 years of media conversion, the most stable media type is clearly |
the DC600 aka Tandberg (and others).
It is clear that there are compatibility issues, as the number of tracks has
changed, and so has the density.
Typically (apart from SLR7) drives are 2 generations backward
write-compatible, and 4-5 generations read-compatible.
Nico |
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Curious George
Guest
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| Posted:
Thu Oct 06, 2005 4:53 am Post subject:
Re: DLT or LTO or AIT for new tape drive? |
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|
On Wed, 5 Oct 2005 21:07:37 +0200, "Nico de Jong"
<first_name@FARUMDATA.DK> wrote:
| Quote: | Well, nothing against Exabyte, but their drives and media, while good,
aren't as bullet-proof, never-fail as my earlier QIC drives, including
a 1 GB native Tandberg drive. But that format seemed to becoming
obsolete, and newer drives couldn't even read some of the older QIC
formats.
compatibility was one issue with QIC. The other is that
"bullet-proof, never-fail" was not typically used to describe them.
In my +20 years of media conversion, the most stable media type is clearly
the DC600 aka Tandberg (and others).
It is clear that there are compatibility issues, as the number of tracks has
changed, and so has the density.
Typically (apart from SLR7) drives are 2 generations backward
write-compatible, and 4-5 generations read-compatible.
Nico
|
I don't doubt her good experiences with a Tandberg. I think you would
agree, though, "QIC" is a very broad category indeed. |
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Nico de Jong
Guest
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| Posted:
Thu Oct 06, 2005 7:26 am Post subject:
Re: DLT or LTO or AIT for new tape drive? |
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|
orge" <cg@email.net> skrev i en meddelelse
news:hdp8k1153irai0nko16biuv5bp29u6p45r@4ax.com...
| Quote: | and newer drives couldn't even read some of the older QIC
formats.
compatibility was one issue with QIC. The other is that
"bullet-proof, never-fail" was not typically used to describe them.
In my +20 years of media conversion, the most stable media type is
clearly
the DC600 aka Tandberg (and others).
I don't doubt her good experiences with a Tandberg. I think you would
agree, though, "QIC" is a very broad category indeed.
You'right. I'm thinking exclusively on the DC600 drives working on SCSI, |
like Tandberg and Archive Viper series (2060 and 2150 IIRC)). Although the
Viper drives are not quite as stable as the Tandberg, I never had
media-related problems, apart from 2 cases where the tape broke.
On the opposite site, I have bad experiences with DDS3 drives. A case comes
to mind where I had to do so forensics work for the State Police. I mounted
the tape in a new drive, and took off the partition with the backup. No
problem. Then the customer came back, and wanted more. I can't recall if it
was another partition or just a "loglist" or whatever. I mounted the tape
again, but nothing happend. Retry, again nothing. I then took the lid of the
drive, and saw that the tape was wound around the motor. Totally destructed,
and I tossed the drive too.
I was not very popular with the State Police, as the data had to used in
court...
Nico |
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Lady Margaret Thatcher
Guest
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| Posted:
Fri Oct 07, 2005 1:24 pm Post subject:
Re: DLT or LTO or AIT for new tape drive? |
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On Wed, 05 Oct 2005 18:33:00 GMT, Curious George <cg@email.net> wrote:
| Quote: | On Wed, 14 Sep 2005 21:56:34 -0700, Lady Margaret Thatcher
It isn't really. SDLT replaces DLT but some backwards-compatability
remains. There are so many DLT systems in service that there should
be no problems coming by tapes & parts for the next few years (which
is all you should expect anyway).
LTO might be nice.
If it is master of the enterprise, that tells me it's reliable. But
it also tells me that it could be too expensive for me, and the native
transfer rates to keep an LTO drive "full" might be more than my LAN
could possibly supply.
I previous asked about "shoeshining" with different formats. Is AIT
less prone to shoeshining than the other formats?
That's software & configuration specific except for some LTO's that
can adjust speed to compensate.
|
Can you be specific about LTOs that can adjust speed? Exabyte claims
their VXA drives are the only ones that can adjust speed. For me
that's important. I like the larger capacities of more recent drives,
but tape speed is an issue.
Thank you
--thatcher- |
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Steve Cousins
Guest
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| Posted:
Fri Oct 07, 2005 7:52 pm Post subject:
Re: DLT or LTO or AIT for new tape drive? |
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|
Lady Margaret Thatcher wrote:
| Quote: |
I previous asked about "shoeshining" with different formats. Is AIT
less prone to shoeshining than the other formats?
That's software & configuration specific except for some LTO's that
can adjust speed to compensate.
Can you be specific about LTOs that can adjust speed? Exabyte claims
their VXA drives are the only ones that can adjust speed. For me
that's important. I like the larger capacities of more recent drives,
but tape speed is an issue.
|
SDLT, DLT 8000, and most LTO drives have variable speed capability. The
only LTO's that don't seem to have it are HP and IBM versions of LTO1. |
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RPR
Guest
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| Posted:
Sun Oct 09, 2005 1:02 am Post subject:
Re: DLT or LTO or AIT for new tape drive? |
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|
FWIW, it is German "kaputt", from Yiddish "kaput", which made its way
into American slang.
Just *had* to throw this in...
Ralf-Peter |
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Curious George
Guest
|
| Posted:
Sun Oct 09, 2005 3:16 am Post subject:
Re: DLT or LTO or AIT for new tape drive? |
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|
On Fri, 07 Oct 2005 10:52:14 -0400, Steve Cousins
<steve.cousins@maine.edu> wrote:
| Quote: | SDLT, DLT 8000, and most LTO drives have variable speed capability. The
only LTO's that don't seem to have it are HP and IBM versions of LTO1.
|
Then why is it only advertized in Seagate LTO-1 and newer HP & IBM
LTO-2's? |
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Lady Margaret Thatcher
Guest
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| Posted:
Mon Oct 10, 2005 2:52 pm Post subject:
Re: DLT or LTO or AIT for new tape drive? |
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|
On 8 Oct 2005 13:02:17 -0700, "RPR" <rohbeck@yahoo.com> wrote:
| Quote: | FWIW, it is German "kaputt", from Yiddish "kaput", which made its way
into American slang.
Just *had* to throw this in...
|
So, nu already?
>Ralf-Peter |
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