[OT] best tape backup system?

[OT] best tape backup system?

[Louis-David Mitterrand]

Hello and sorry for the OT post, but I felt linux raid administrators
can be also very knowledgable about best-of-breed tape backup systems
for their linux servers.

I admin serveral linux servers with software root raid1/5 and am very
happy about their performance and reliability. Up to now our backup
strategy has consisted in daily offsite incremental rsync backups to
other raid5 linux servers. But I feel a bit nervous about not having
offline backups such as tapes that can be restored in the event our
servers AND their mirrors suffer catastrophic failure or exploitation.

I am considering getting a Sony SAIT 3 with 500G/1TB tapes, which seems
like a nice solution for backuping a whole server on a single tape.

Has anyone used that hardware and can comment on its performance,
linux-compatibility or otherwise?

Is there a better solution out there?

Is it worth waiting a short while for some new upcoming technology?


Thanks for reading and have a nice day!

-- 
I feel naked outside of Vim. -- Ted Knab

Re: [OT] best tape backup system?

[Lajber Zoltan]

On Tue, 22 Feb 2005, Louis-David Mitterrand wrote:

> Is there a better solution out there?

We using an "59P6744 200/400GB LTO Full-High Tape Drive" with great
resuslt. It made a full 180G backup within 100 minutes. We are using the
"tob" script for full and differential backups.

Bye,
-=Lajbi=----------------------------------------------------------------
 LAJBER Zoltan               Szent Istvan Egyetem,  Informatika Hivatal
   engineer: a mechanism for converting caffeine into designs.

Re: [OT] best tape backup system?

[Gordon Henderson]

On Tue, 22 Feb 2005, Louis-David Mitterrand wrote:

> I am considering getting a Sony SAIT 3 with 500G/1TB tapes, which seems
> like a nice solution for backuping a whole server on a single tape.

I've been using DLT tapes for many years now, prior to that DAT tapes and
Exabytes before that... Capacity is the one thing that you struggle with
on tapes, and most of the servers I've built recently have had their disk
partition sizes matched to the best DLT tape drive we could afford at the
time. Your Sony tapes of 500GB (native, I presume and up to 1TB
compressed) look quite attractive though, but I've no experience of how
reliable they might be...

Beware of the compression though - it all depends on what your data-set is
- I can rarely get much beyond 1.3 times the native/raw capacity, but if
all you are storing is text files you may well achieve close to 2x raw
capacity.

One thing I'd recomend is getting a seprate SCSI card just for the tape
drive if possible, rather than daisy-chain it to the end of an existing
SCSI bus with drives. You'll improve performance, and you'll also be able
to hot remove/add the tape drive should you need to (assuming external
drives) without the wory of upsetting a bus with disks passing live data.
I'm moving towards external drives now to make it easier to replace the
drive should it ever fail while maintaining server avalability.

> Has anyone used that hardware and can comment on its performance,
> linux-compatibility or otherwise?
>
> Is there a better solution out there?

Things that I was looking for was long-term viability - (eg) what does the
road-map look like for the Sony drives. Availability (and price!) of
media, and so on, as well as things like being able to read older tapes on
newer drives, should you get a bigger drive in the future.

> Is it worth waiting a short while for some new upcoming technology?

Personally, no. Strike while the iron is hot, Carpe Jugulum, and stuff
like that! Get the best you can afford today, otherwise you'll always be
chasing that next best thing thats just round the corner without actually
implementing a solution.

Other things to consider is the software you use to do the backup - I've
been using Amanda for many (>12 ish) years with good results. It uses
standard dump/xfsdump or tar as the underlying tape storage format, so
even if you lose the Amanda database, you can still restore from the
tapes, however, I have to admit that Amanda might not be the easiest thing
to install for the first time and I've not actually looked for an
alternative recently, so don't really have a handle on what else is out
there, but you want something that will email you with the right 'next'
tape to put in and email you the results, as well as something that will
tell you what tape holds the latest versions of what files (especially if
you ever get into the dreaded situation where you have to do incremental
dumps) Amanda also checks that you have the right tape in before it
overwrites it (it keeps a seaprate file at the start of the tape with the
tape name) This is useful when faced with a dozen tape drives and you are
in a hurry...

Tar (or star) might seem like a good way to dump a filesystem, but it's
harder to extract a single file or directory off the tape unless you have
a good index of everything thats on the tape. Restore has an interactive
mode which lets you browse the index of the tape and add files and folders
as needed before hitting the extract button and going away for several
cups of coffee while it does its thing.

There are potential problems with dump - there is a small but finite
chance of data corruption when you dump (or even tar) a live filesystem,
so I've been building servers with 2x the disk capacity and I rsync the
live partition to the 'yesterday' partition, then remount that read-only
and dump from that.  So-far so good, and the punters get a instant restore
if they accidentally delete a file. (Accidental file deletion is a PITA,
taking sometimes many hours to restore from tape)

Ah, found something relevant:

  http://dump.sourceforge.net/isdumpdeprecated.html

That article is well-worth a read.

Do check your restore mechanism, whatever method you use! Do deliberately
remove (rename!) a file or directory and try to get it back from tape, so
you are familiar with the mechanisms should you be called to do so for
real. Restoring a entire partition is usually a lot easier than just a
single file though, and don't forget to archive your root partition (if
it's separate, so you can get back all your changes to the init files,
etc. if you ever have to restore from scratch.

Good luck,

Gordon

RE: [OT] best tape backup system?

[Guy]

I have NOT been able to share a SCSI cable/card with disks and a tape drive.
Tried for days.  I would get disk errors, or timeouts.  I corrected the
problem by putting the tape drive on a dedicated SCSI bus/card.  I don't
recall the details of the failures, since it has been well over a year now.
But I do know I only had problems while using the tape drive and the disks
at the same time.  Like, during a backup.  The disks were happy while the
tape drive was idle.  I also swapped parts, it had no effect.  I assumed
Linux does not like to share SCSI.

I have not had problems with 2 or more tape drives on the same SCSI
bus/card.  I think I had 3 at one time.

Amanda...  The last time I checked, incremental backups require a different
tape each time.  You will need a lot of tapes.  If a full backup fits on a
single tape, just do a full backup each night.  I need many tapes to do a
full backup, but a single tape can hold many daily incremental backups.  I
deemed Amanda to wasteful for me.  I use home made scripts and cpio and do a
full backup about once per month, and do nightly incremental backups to 1
tape.  Once the daily tape is full I do another full backup.  Works very
well for me.  But, restoring is a pain, but that is very rare for me, only
once in 1+ years, so far.  My scripts seek the tape as required, so I can
eject the tape if needed, as long as I put it back in time for the nightly
backup.

If anyone gets 1.3 to 1 compression, that is real good!!!!  IMO.  The last
time I checked, I got about 1.1 to 1.  What a marketing scam!!!!

Guy

-----Original Message-----
From: linux-raid-owner@vger.kernel.org
[mailto:linux-raid-owner@vger.kernel.org] On Behalf Of Gordon Henderson
Sent: Tuesday, February 22, 2005 10:41 AM
To: Louis-David Mitterrand
Cc: linux-raid@vger.kernel.org
Subject: Re: [OT] best tape backup system?

On Tue, 22 Feb 2005, Louis-David Mitterrand wrote:

> I am considering getting a Sony SAIT 3 with 500G/1TB tapes, which seems
> like a nice solution for backuping a whole server on a single tape.

I've been using DLT tapes for many years now, prior to that DAT tapes and
Exabytes before that... Capacity is the one thing that you struggle with
on tapes, and most of the servers I've built recently have had their disk
partition sizes matched to the best DLT tape drive we could afford at the
time. Your Sony tapes of 500GB (native, I presume and up to 1TB
compressed) look quite attractive though, but I've no experience of how
reliable they might be...

Beware of the compression though - it all depends on what your data-set is
- I can rarely get much beyond 1.3 times the native/raw capacity, but if
all you are storing is text files you may well achieve close to 2x raw
capacity.

One thing I'd recomend is getting a seprate SCSI card just for the tape
drive if possible, rather than daisy-chain it to the end of an existing
SCSI bus with drives. You'll improve performance, and you'll also be able
to hot remove/add the tape drive should you need to (assuming external
drives) without the wory of upsetting a bus with disks passing live data.
I'm moving towards external drives now to make it easier to replace the
drive should it ever fail while maintaining server avalability.

> Has anyone used that hardware and can comment on its performance,
> linux-compatibility or otherwise?
>
> Is there a better solution out there?

Things that I was looking for was long-term viability - (eg) what does the
road-map look like for the Sony drives. Availability (and price!) of
media, and so on, as well as things like being able to read older tapes on
newer drives, should you get a bigger drive in the future.

> Is it worth waiting a short while for some new upcoming technology?

Personally, no. Strike while the iron is hot, Carpe Jugulum, and stuff
like that! Get the best you can afford today, otherwise you'll always be
chasing that next best thing thats just round the corner without actually
implementing a solution.

Other things to consider is the software you use to do the backup - I've
been using Amanda for many (>12 ish) years with good results. It uses
standard dump/xfsdump or tar as the underlying tape storage format, so
even if you lose the Amanda database, you can still restore from the
tapes, however, I have to admit that Amanda might not be the easiest thing
to install for the first time and I've not actually looked for an
alternative recently, so don't really have a handle on what else is out
there, but you want something that will email you with the right 'next'
tape to put in and email you the results, as well as something that will
tell you what tape holds the latest versions of what files (especially if
you ever get into the dreaded situation where you have to do incremental
dumps) Amanda also checks that you have the right tape in before it
overwrites it (it keeps a seaprate file at the start of the tape with the
tape name) This is useful when faced with a dozen tape drives and you are
in a hurry...

Tar (or star) might seem like a good way to dump a filesystem, but it's
harder to extract a single file or directory off the tape unless you have
a good index of everything thats on the tape. Restore has an interactive
mode which lets you browse the index of the tape and add files and folders
as needed before hitting the extract button and going away for several
cups of coffee while it does its thing.

There are potential problems with dump - there is a small but finite
chance of data corruption when you dump (or even tar) a live filesystem,
so I've been building servers with 2x the disk capacity and I rsync the
live partition to the 'yesterday' partition, then remount that read-only
and dump from that.  So-far so good, and the punters get a instant restore
if they accidentally delete a file. (Accidental file deletion is a PITA,
taking sometimes many hours to restore from tape)

Ah, found something relevant:

  http://dump.sourceforge.net/isdumpdeprecated.html

That article is well-worth a read.

Do check your restore mechanism, whatever method you use! Do deliberately
remove (rename!) a file or directory and try to get it back from tape, so
you are familiar with the mechanisms should you be called to do so for
real. Restoring a entire partition is usually a lot easier than just a
single file though, and don't forget to archive your root partition (if
it's separate, so you can get back all your changes to the init files,
etc. if you ever have to restore from scratch.

Good luck,

Gordon
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RE: [OT] best tape backup system?

[Gordon Henderson]

On Tue, 22 Feb 2005, Guy wrote:

> I have NOT been able to share a SCSI cable/card with disks and a tape
> drive. Tried for days.  I would get disk errors, or timeouts.  I
> corrected the problem by putting the tape drive on a dedicated SCSI
> bus/card.  I don't recall the details of the failures, since it has been
> well over a year now. But I do know I only had problems while using the
> tape drive and the disks at the same time.  Like, during a backup.  The
> disks were happy while the tape drive was idle.  I also swapped parts,
> it had no effect.  I assumed Linux does not like to share SCSI.

Linux is fine with multiple devices on SCSI - scanners, drives, tapes. I
haven't had problems with these combinations. The "usual culprit" is
termination. Either not enough or too much! You need termination at both
ends of the bus - one end is usually (but not always) the SCSI card, and
all cards I've used in the past few years have had the ability to turn
termination on or off (You turn it off if the card is not at one end of
the bus) Some tape drives I've used also have the ability to turn
termination on, or not - sometimes you set the drive number to one range
for termination, another range for not (eg. 0-7 no termination, 8-15
active termination). It's a real PITA to get right at times.

> I have not had problems with 2 or more tape drives on the same SCSI
> bus/card.  I think I had 3 at one time.
>
> Amanda...  The last time I checked, incremental backups require a different
> tape each time.  You will need a lot of tapes.  If a full backup fits on a
> single tape, just do a full backup each night.  I need many tapes to do a
> full backup, but a single tape can hold many daily incremental backups.  I
> deemed Amanda to wasteful for me.  I use home made scripts and cpio and do a
> full backup about once per month, and do nightly incremental backups to 1
> tape.  Once the daily tape is full I do another full backup.  Works very
> well for me.  But, restoring is a pain, but that is very rare for me, only
> once in 1+ years, so far.  My scripts seek the tape as required, so I can
> eject the tape if needed, as long as I put it back in time for the nightly
> backup.

Yup. One tape per backup run with Amanda. Way back when tape capacity
exceeded disk capacity, I used Amanda to backup many machines to one tape
every night - that was its original strength, the ability to backup many
machines over the LAN to one tape drive. These days with disk capacities
generally exceeding tapes, it's not like that anymore (although I still
have some smaller servers backed up to a non-local tape drive for reasons
of economy)

> If anyone gets 1.3 to 1 compression, that is real good!!!!  IMO.  The
> last time I checked, I got about 1.1 to 1.  What a marketing scam!!!!

Compression is always a weirdism - I'm guessing your data is music, video
or pictures - stuff thats already compressed which won't compress twice.
Typical "officy" type data would be stuff that generally compresses well -
text documents, spreadsheets, program source code (& compiled binaries)
etc. Amanda can compress data and in some cases better than the tape
drives (using gzip, etc), but it's slow and makes restoring more
interesting...

I think Sony are claiming 2.3:1 with their new tapes - well, they'll get
that with text-files, but nothing near that with anything else!

Gordon

RE: [OT] best tape backup system?

[Guy]

In my case, I am sure I had the termination correct.  I normally don't set
the SCSI card to auto termination, since I don't trust it!  But I did try
every valid permutation.  On non-Linux systems, I have never had problems
mixing disks with tapes or anything else.  And since I swapped terminators,
cables and cards, the only hardware that could be at fault would be the tape
or disk drives.  But, they are still working to this day, just on separate
SCSI cards.

If I recall, I once had a Unix system where someone created about 128 Gig of
sparse files.  I backed up the files to a DDS-3 tape (12-24 Gig).  The
backup took more than 24 hours.  That is better than 10 to 1.  :)  So, yes,
giving the correct data, 2 to 1 can be done, but not in the real world.
IMO.

Guy

-----Original Message-----
From: linux-raid-owner@vger.kernel.org
[mailto:linux-raid-owner@vger.kernel.org] On Behalf Of Gordon Henderson
Sent: Tuesday, February 22, 2005 12:40 PM
To: Guy
Cc: linux-raid@vger.kernel.org
Subject: RE: [OT] best tape backup system?

On Tue, 22 Feb 2005, Guy wrote:

> I have NOT been able to share a SCSI cable/card with disks and a tape
> drive. Tried for days.  I would get disk errors, or timeouts.  I
> corrected the problem by putting the tape drive on a dedicated SCSI
> bus/card.  I don't recall the details of the failures, since it has been
> well over a year now. But I do know I only had problems while using the
> tape drive and the disks at the same time.  Like, during a backup.  The
> disks were happy while the tape drive was idle.  I also swapped parts,
> it had no effect.  I assumed Linux does not like to share SCSI.

Linux is fine with multiple devices on SCSI - scanners, drives, tapes. I
haven't had problems with these combinations. The "usual culprit" is
termination. Either not enough or too much! You need termination at both
ends of the bus - one end is usually (but not always) the SCSI card, and
all cards I've used in the past few years have had the ability to turn
termination on or off (You turn it off if the card is not at one end of
the bus) Some tape drives I've used also have the ability to turn
termination on, or not - sometimes you set the drive number to one range
for termination, another range for not (eg. 0-7 no termination, 8-15
active termination). It's a real PITA to get right at times.

> I have not had problems with 2 or more tape drives on the same SCSI
> bus/card.  I think I had 3 at one time.
>
> Amanda...  The last time I checked, incremental backups require a
different
> tape each time.  You will need a lot of tapes.  If a full backup fits on a
> single tape, just do a full backup each night.  I need many tapes to do a
> full backup, but a single tape can hold many daily incremental backups.  I
> deemed Amanda to wasteful for me.  I use home made scripts and cpio and do
a
> full backup about once per month, and do nightly incremental backups to 1
> tape.  Once the daily tape is full I do another full backup.  Works very
> well for me.  But, restoring is a pain, but that is very rare for me, only
> once in 1+ years, so far.  My scripts seek the tape as required, so I can
> eject the tape if needed, as long as I put it back in time for the nightly
> backup.

Yup. One tape per backup run with Amanda. Way back when tape capacity
exceeded disk capacity, I used Amanda to backup many machines to one tape
every night - that was its original strength, the ability to backup many
machines over the LAN to one tape drive. These days with disk capacities
generally exceeding tapes, it's not like that anymore (although I still
have some smaller servers backed up to a non-local tape drive for reasons
of economy)

> If anyone gets 1.3 to 1 compression, that is real good!!!!  IMO.  The
> last time I checked, I got about 1.1 to 1.  What a marketing scam!!!!

Compression is always a weirdism - I'm guessing your data is music, video
or pictures - stuff thats already compressed which won't compress twice.
Typical "officy" type data would be stuff that generally compresses well -
text documents, spreadsheets, program source code (& compiled binaries)
etc. Amanda can compress data and in some cases better than the tape
drives (using gzip, etc), but it's slow and makes restoring more
interesting...

I think Sony are claiming 2.3:1 with their new tapes - well, they'll get
that with text-files, but nothing near that with anything else!

Gordon
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Re: [OT] best tape backup system?

[Michael Tokarev]

Guy wrote:
> I have NOT been able to share a SCSI cable/card with disks and a tape drive.
> Tried for days.  I would get disk errors, or timeouts.  I corrected the
> problem by putting the tape drive on a dedicated SCSI bus/card.  I don't
> recall the details of the failures, since it has been well over a year now.
> But I do know I only had problems while using the tape drive and the disks
> at the same time.  Like, during a backup.  The disks were happy while the
> tape drive was idle.  I also swapped parts, it had no effect.  I assumed
> Linux does not like to share SCSI.

There may be various reasons for this, and i think all of them are related
to hardware only, esp. to the SCSI bus.  Eg, some modern disk drives don't
understand SE mode anymore, so can't be plugged into an scsi bus with at
least one SE device.  On the other hand, it was qutie common for esp. old
tapes to NOT understand LVD mode.  Obviously you can't mix that sort of
devices on the same bus.  I guess the bus where you drives are is in LVD
mode while tapes works in SE mode...

BTW, I've seen quite modern tape drive with an old scsi connector (I don't
even remember anymore how it's called -- the one which looks pretty like
an IDE connector but a bit wider and with more (80?) pins; with max speed
of 20Mb/sec aka 10MHz or so) inside the case and with an adaptor for current
68pin scsi connector standard.  Obviously it works in SE mode only (that bus
worked in that mode only).  Don't remember which vendor that drive was...

/mjt

RE: [OT] best tape backup system?

[Guy]

I know a thing or 2 about SCSI.  I know I had it correct.  1 config was all
wide LVD (2940U2W).  My card has a LVD and a SE port on the same logical
SCSI bus.  Another config was wide LVD disks and a narrow SE tape.  Another,
my disks support SE, I had all SE wide and narrow.  Correct terminators in
each case.  I also tried a 2940UW, no LVD, all SE.  All configs worked if I
only used the disks or the tape drives, but failed if I used disks and tape
at the same time.

I am convinced I had many valid configurations, none worked until I used 2
SCSI cards.  My system has grown, it now has 5 SCSI buses, 17 disk drives
and 2 tape drives.  Works just fine.  But no tape on the same SCSI bus as
disks.

Guy


-----Original Message-----
From: linux-raid-owner@vger.kernel.org
[mailto:linux-raid-owner@vger.kernel.org] On Behalf Of Michael Tokarev
Sent: Tuesday, February 22, 2005 4:53 PM
To: linux-raid@vger.kernel.org
Subject: Re: [OT] best tape backup system?

Guy wrote:
> I have NOT been able to share a SCSI cable/card with disks and a tape
drive.
> Tried for days.  I would get disk errors, or timeouts.  I corrected the
> problem by putting the tape drive on a dedicated SCSI bus/card.  I don't
> recall the details of the failures, since it has been well over a year
now.
> But I do know I only had problems while using the tape drive and the disks
> at the same time.  Like, during a backup.  The disks were happy while the
> tape drive was idle.  I also swapped parts, it had no effect.  I assumed
> Linux does not like to share SCSI.

There may be various reasons for this, and i think all of them are related
to hardware only, esp. to the SCSI bus.  Eg, some modern disk drives don't
understand SE mode anymore, so can't be plugged into an scsi bus with at
least one SE device.  On the other hand, it was qutie common for esp. old
tapes to NOT understand LVD mode.  Obviously you can't mix that sort of
devices on the same bus.  I guess the bus where you drives are is in LVD
mode while tapes works in SE mode...

BTW, I've seen quite modern tape drive with an old scsi connector (I don't
even remember anymore how it's called -- the one which looks pretty like
an IDE connector but a bit wider and with more (80?) pins; with max speed
of 20Mb/sec aka 10MHz or so) inside the case and with an adaptor for current
68pin scsi connector standard.  Obviously it works in SE mode only (that bus
worked in that mode only).  Don't remember which vendor that drive was...

/mjt
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Re: [OT] best tape backup system?

[Michael Tokarev]

Guy wrote:
> I know a thing or 2 about SCSI.  I know I had it correct.  1 config was all
> wide LVD (2940U2W).  My card has a LVD and a SE port on the same logical
> SCSI bus.

I was surprized once when I noticied such "logical SCSI bus" really isn't
"logical" per se.  I mean, if I plug ANY device into the "SE port", all
devices, including the ones attached to "LVD port" switches to SE mode.
Another channel - yes, sure, but not another port (connector) on the
same channel.  Well, I can't say for all vendors and all cards, but the
ones we have here (mostly adaptec and ncr/sym) works this way.  For example,
Adaptec AHA-3940U2x controller: it's 2-channel card with 3 ports, two
68pin LVD/SE (one per channel) and one older "scsi-like-ide" connector
attached to 1st channel -- any device attached to this last connector
forces the whole 1st channel to go into SE mode, and no LVD-only device
works (in fact, it does not work at all in this case with any LVD-only
device attached).

>   Another config was wide LVD disks and a narrow SE tape.  Another,
> my disks support SE, I had all SE wide and narrow.  Correct terminators in
> each case.  I also tried a 2940UW, no LVD, all SE.  All configs worked if I
> only used the disks or the tape drives, but failed if I used disks and tape
> at the same time.

Well, this is weird.  We have numerous configurations with mixed tapes and
disks (and other stuff) and had no single problem so far, everything just
works (except of that obvious LVD vs SE issue).  Including 2940UW and other
controllers.

/mjt

RE: [OT] best tape backup system?

[Guy]

We must be in 2 different worlds!!!

I can have wide LVD and narrow SE on the same card (2940U2W).  And wide
ultra and narrow SE on the same card (2940UW).  That is why the card is so
good.  IMO.  Just not with linux.  The OS that must not be named, supports
the above.  :(  In fact, I have a PC with a 2940UW with 2 disks (UW), 2 CDs,
1 DDS3 and a zip drive.  All happy with OS to not be named 98.  Maybe I
should try knopix, and see if that system likes Linux.

However, as I said before.  I did not swap out every component.  I used the
same disks every time, but did swap the data cables, tape drives, SCSI cards
and terminators.  But those disks still work today in U2W (LVD-80) mode.

My last attempt to mix SCSI disks and tapes was over 1 year ago, using RH9.
On previous attempts I would have used RH7.  I don't recall ever using RH8.

Guy

-----Original Message-----
From: linux-raid-owner@vger.kernel.org
[mailto:linux-raid-owner@vger.kernel.org] On Behalf Of Michael Tokarev
Sent: Wednesday, February 23, 2005 1:29 PM
To: linux-raid@vger.kernel.org
Subject: Re: [OT] best tape backup system?

Guy wrote:
> I know a thing or 2 about SCSI.  I know I had it correct.  1 config was
all
> wide LVD (2940U2W).  My card has a LVD and a SE port on the same logical
> SCSI bus.

I was surprized once when I noticied such "logical SCSI bus" really isn't
"logical" per se.  I mean, if I plug ANY device into the "SE port", all
devices, including the ones attached to "LVD port" switches to SE mode.
Another channel - yes, sure, but not another port (connector) on the
same channel.  Well, I can't say for all vendors and all cards, but the
ones we have here (mostly adaptec and ncr/sym) works this way.  For example,
Adaptec AHA-3940U2x controller: it's 2-channel card with 3 ports, two
68pin LVD/SE (one per channel) and one older "scsi-like-ide" connector
attached to 1st channel -- any device attached to this last connector
forces the whole 1st channel to go into SE mode, and no LVD-only device
works (in fact, it does not work at all in this case with any LVD-only
device attached).

>   Another config was wide LVD disks and a narrow SE tape.  Another,
> my disks support SE, I had all SE wide and narrow.  Correct terminators in
> each case.  I also tried a 2940UW, no LVD, all SE.  All configs worked if
I
> only used the disks or the tape drives, but failed if I used disks and
tape
> at the same time.

Well, this is weird.  We have numerous configurations with mixed tapes and
disks (and other stuff) and had no single problem so far, everything just
works (except of that obvious LVD vs SE issue).  Including 2940UW and other
controllers.

/mjt
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Re: [OT] best tape backup system?

[Jon Lewis]

On Tue, 22 Feb 2005, Louis-David Mitterrand wrote:

> I am considering getting a Sony SAIT 3 with 500G/1TB tapes, which seems
> like a nice solution for backuping a whole server on a single tape.
>
> Has anyone used that hardware and can comment on its performance,
> linux-compatibility or otherwise?
>
> Is there a better solution out there?

Better depends on what you want/need/can afford.  Last time I was tape
shopping, I thought this would be a good compromise on the need/can
afford:
Exabyte VXA-2 Packetloader 1x10

Native tape capacity is 800gb.  The only downside is, no magazine...it
stores the tapes in an internal carosel accessed from the front, one
position at a time.  For a bit more $, they have magazine based tape
library systems with VXA-2 drives.

Anyone used these?  I'd still like one.

----------------------------------------------------------------------
 Jon Lewis                   |  I route
 Senior Network Engineer     |  therefore you are
 Atlantic Net                |
_________ http://www.lewis.org/~jlewis/pgp for PGP public key_________

Re: [OT] best tape backup system?

[Alvin Oga]

On Tue, 22 Feb 2005, Jon Lewis wrote:

> On Tue, 22 Feb 2005, Louis-David Mitterrand wrote:
> 
> > I am considering getting a Sony SAIT 3 with 500G/1TB tapes, which seems
> > like a nice solution for backuping a whole server on a single tape.
> >
> > Has anyone used that hardware and can comment on its performance,
> > linux-compatibility or otherwise?
> >
> > Is there a better solution out there?
> 
> Better depends on what you want/need/can afford.  Last time I was tape
> shopping, I thought this would be a good compromise on the need/can
> afford:
> Exabyte VXA-2 Packetloader 1x10
> 
> Native tape capacity is 800gb.  The only downside is, no magazine...it
> stores the tapes in an internal carosel accessed from the front, one
> position at a time.  For a bit more $, they have magazine based tape
> library systems with VXA-2 drives.

for 1TB of storage ... i'd put the data on 4 disks ( raided ) 
and take the disks and put in nice bubble wrap and nice cushion 

:-)

don't pop the bubbles 

and yup.. i want the fast restore of 1TB of data too which to me
is more important than the $50 or $100 tape costs (plus the tape drive)
vs $600 set of 1TB disk

c ya
alvin

i keep wondering why people pay $150K for 1TB brandname tape subsystems ..
:-)

Re: [OT] best tape backup system?

[Jon Lewis]

On Tue, 22 Feb 2005, Alvin Oga wrote:

> > Better depends on what you want/need/can afford.  Last time I was tape
> > shopping, I thought this would be a good compromise on the need/can
> > afford:
> > Exabyte VXA-2 Packetloader 1x10
> >
> > Native tape capacity is 800gb.  The only downside is, no magazine...it
> > stores the tapes in an internal carosel accessed from the front, one
> > position at a time.  For a bit more $, they have magazine based tape
> > library systems with VXA-2 drives.
>
> for 1TB of storage ... i'd put the data on 4 disks ( raided )
> and take the disks and put in nice bubble wrap and nice cushion

I should clarify, that's 80GB per tape...so 800GB native assumes you have
10 tapes in the unit.

> i keep wondering why people pay $150K for 1TB brandname tape subsystems ..

I wouldn't pay that much...but I think the "common wisdom" is that tape is
more durable/portable than disks.  Once upon a time, it was cheaper than
disks too...but that's no longer the case.  It's part of why my plan to
buy a bunch of Exabyte stuff got shot down and instead we bought P4's with
1TB SATA-RAID5 arrays to use as "backup servers".

----------------------------------------------------------------------
 Jon Lewis                   |  I route
 Senior Network Engineer     |  therefore you are
 Atlantic Net                |
_________ http://www.lewis.org/~jlewis/pgp for PGP public key_________

Re: [OT] best tape backup system?

[David Dougall]

Not sure if it is important to many people, but tapes take a lot less
electricity than online disks.
--David Dougall


On Tue, 22 Feb 2005, Jon Lewis wrote:

> On Tue, 22 Feb 2005, Alvin Oga wrote:
>
> > > Better depends on what you want/need/can afford.  Last time I was tape
> > > shopping, I thought this would be a good compromise on the need/can
> > > afford:
> > > Exabyte VXA-2 Packetloader 1x10
> > >
> > > Native tape capacity is 800gb.  The only downside is, no magazine...it
> > > stores the tapes in an internal carosel accessed from the front, one
> > > position at a time.  For a bit more $, they have magazine based tape
> > > library systems with VXA-2 drives.
> >
> > for 1TB of storage ... i'd put the data on 4 disks ( raided )
> > and take the disks and put in nice bubble wrap and nice cushion
>
> I should clarify, that's 80GB per tape...so 800GB native assumes you have
> 10 tapes in the unit.
>
> > i keep wondering why people pay $150K for 1TB brandname tape subsystems ..
>
> I wouldn't pay that much...but I think the "common wisdom" is that tape is
> more durable/portable than disks.  Once upon a time, it was cheaper than
> disks too...but that's no longer the case.  It's part of why my plan to
> buy a bunch of Exabyte stuff got shot down and instead we bought P4's with
> 1TB SATA-RAID5 arrays to use as "backup servers".
>
> ----------------------------------------------------------------------
>  Jon Lewis                   |  I route
>  Senior Network Engineer     |  therefore you are
>  Atlantic Net                |
> _________ http://www.lewis.org/~jlewis/pgp for PGP public key_________
> -
> To unsubscribe from this list: send the line "unsubscribe linux-raid" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>
>
>

Re: [OT] best tape backup system?

[Mark Hahn]

> Not sure if it is important to many people, but tapes take a lot less
> electricity than online disks.

do you really care?  an active disk is about 15W, inactive 5W
and asleep nearly zero.  even assuming idle-but-spinning, 
I make that as about $2/year.

tapes are wonderful in every way except one: they're finicky
and difficult to care for properly.  for instance, do you have 
a humidity and temperature-controlled place to store them?
and have you actually logged the temp/hum for that to see 
whether, for instance, it gets warm on weekends?

if I were forced to use tapes, I would insist on making 2+ copies
of everything.  note that this clearly hurt's tape's competitiveness
WRT price, size, bandwidth, etc.

I don't see any new tape installations that are not driven by 
secondary factors such as big piles of old data already on tape,
or someone wanting to physically move the media into a vault.

(on that topic, I don't buy the idea that tape's less vulnerable 
to hacking, either.  just because your backup is on disk doesn't
mean that it's online or accessible.  similarly, just because 
your tape is in a separate cabinet doesn't mean that a sufficiently
motivated badguy could not get the tape put into some drive...)

regards, mark hahn.
(buying many TB of disk this year and no tape)

Re: [OT] best tape backup system?

[berk walker]

And worse yet, you have to run them to the end and then rewind them if 
you are going to keep the data for long [the magnetic fields affect 
layers near them]. An array of RAID1 disks, which sleep deeply [off] 
between uses would probably be affordable, and last MUCH longer.

Just my 2 cents worth-
ya, well, that's what you get for 2 cents.
b-

Mark Hahn wrote:

>>Not sure if it is important to many people, but tapes take a lot less
>>electricity than online disks.
>>    
>>
>
>do you really care?  an active disk is about 15W, inactive 5W
>and asleep nearly zero.  even assuming idle-but-spinning, 
>I make that as about $2/year.
>
>tapes are wonderful in every way except one: they're finicky
>and difficult to care for properly.  for instance, do you have 
>a humidity and temperature-controlled place to store them?
>and have you actually logged the temp/hum for that to see 
>whether, for instance, it gets warm on weekends?
>
>if I were forced to use tapes, I would insist on making 2+ copies
>of everything.  note that this clearly hurt's tape's competitiveness
>WRT price, size, bandwidth, etc.
>
>I don't see any new tape installations that are not driven by 
>secondary factors such as big piles of old data already on tape,
>or someone wanting to physically move the media into a vault.
>
>(on that topic, I don't buy the idea that tape's less vulnerable 
>to hacking, either.  just because your backup is on disk doesn't
>mean that it's online or accessible.  similarly, just because 
>your tape is in a separate cabinet doesn't mean that a sufficiently
>motivated badguy could not get the tape put into some drive...)
>
>regards, mark hahn.
>(buying many TB of disk this year and no tape)
>
>-
>To unsubscribe from this list: send the line "unsubscribe linux-raid" in
>the body of a message to majordomo@vger.kernel.org
>More majordomo info at  http://vger.kernel.org/majordomo-info.html
>
>.
>
>  
>

Re: [OT] best tape backup system?

[Alvin Oga]

hi ya

On Tue, 22 Feb 2005, Jon Lewis wrote:

> I should clarify, that's 80GB per tape...so 800GB native assumes you have
> 10 tapes in the unit.

yup...seen those puppies too ... too much headache for me
 
> > i keep wondering why people pay $150K for 1TB brandname tape subsystems ..
> 
> I wouldn't pay that much...

the odd part is people do :-) just because its "name branded enterprise
blah blah"

> but I think the "common wisdom" is that tape is
> more durable/portable than disks.  Once upon a time, it was cheaper than
> disks too...but that's no longer the case.

yup ... and disks have become more reliable 

tapes still ahve the same problem they always had ... the heads need
to be cleaned, and if the drive unit goes in for repair, you have no
alternative options 
	- i usually get those calls, from panicky folks, which there
	is no solution other than buy 2 tape drives or buy disk-based
	backups in addition to tapes if they like tapes

both tape and disk backups have its purposes and reasons

>  It's part of why my plan to
> buy a bunch of Exabyte stuff got shot down and instead we bought P4's with
> 1TB SATA-RAID5 arrays to use as "backup servers".

i'd buy 2 disk based backups, because one has to backup the backup server
:-)

	- disks is cheap, compared to loss of 1TB of corp data
	or 10TB of corp data is more along the lines of fun when things
	become interesting  :-)

------

david> Not sure if it is important to many people, but tapes take a lot
david> less electricity than online disks.

i doubt that it'd be a factor in buying tapes vs disks, but one
never knows :-0

they should be more worried about magnets and phones next to the tape
or tapes under the old fashion crt's

- you'd be surprise what one finds, when one goes into "server rooms" 
  which i guess is the fun part, fixing their problems

c ya
alvin