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Why bother with a tape drive?

I've got a sql 2k database, something around 20GB.  I've been using BackupExec 9.0 to do backup to our Sony Autoloader tape drive.  (50GB capacity)

Between all the problems with BackupExec failing for various reasons, and not being able to control the tape drive, I'm wondering if using a tape backup solution is worthwhile any more.  Anyone ever looking at BackupExec's support site for BackupExec Windows Servers will be horrified.  They issue hotfixes that break all the time, and then instruct you to call their support desk, modify the registry, and back it out.  All the while leaving those same hotfixesx up there for download.  Its great to see a download that says "hotfix 19 - download here".  And then a line down it says "hotfix 19 causes all tape drives to go offline..."


Ie, I can throw some SATA disks on either a RAID 0 array, or maybe a RAID 1 array, for a few hundred dollars.  This drive can have many times the capacity of a tape backup, and it is faster to do the backup, and doesn't have all the problems of a tape restore.

Sure, I can't really take the tapes out, but i periodically download the db offline anyway, so who cares about that?

Any comments about using tape backup versus disk backups?

Fed up with tape backups
Monday, August 09, 2004

Send it to the bit bucket!

Just kidding :D

Li-fan Chen
Monday, August 09, 2004

Can't comment on the merits in your situation.  Some of the reasons our site uses tape backups instead of disks:  power consumption (and the related cooling), disks crash more often then tapes break (we've even had multiple disks in a RAID crash simultaneously).  We are dealing in many terrabytes of data though, so our priorities and concerns won't be the same as yours.

madking
Monday, August 09, 2004

Advantages of tape:
1) The heads are seperated from the media, so if the heads fail, the media is still (assuming that the tape wasn't irevocably crinkled by the transport) OK.
2) Tapes are normally stored offline.  Combined with #1, this means that certain types of massive disasters are more easily survivable.  This includes one of the more common ways for computers to die -- lightning strikes and other power surges.
3) Tapes are more durable than disks.  They can handle being dropped and, if they are damage, are often times easier to repair.

See, I think that the largest problem is that it seems like nobody can really write a good backup package, not the inherent properties of the drive.  And the problem is that an upstart wouldn't be trusted, so it would be awfully hard to break into that space anyway.

Flamebait Sr.
Monday, August 09, 2004

[DISCLAIMER: I work for a company which sells a backup & restore product]

Disk-to-disk is becoming a lot more popular, especially with new setups.  The problem with D2D is usually cost / reliability, but that is coming down a lot lately.

The things you need to look at are:
* do you need to move data offsite? If yes, tapes simplify life
* do you need the ability to archive / warehouse?  Again, tapes are more mature
* what is the reliabilty threshold ? Disks fail more than tapes, on the whole.

Another thing you might want to do is look at another backup product ;-)

Sassy
Monday, August 09, 2004


Tape is nice because it's easy to store offsite etc.  Try Ultrabac.  I too didn't like Backup exec.  Way to f'ing bloated.

Sysadmin
Monday, August 09, 2004

Joel talked about how he does it.

http://joelonsoftware.com/items/2004/01/19.html

*I* personally have found that tape media is not reliable.  I've had several instances where a tape was unreadable when the backup was needed.  I would not trust a single copy of a tape as a reliable backup.

AMS
Monday, August 09, 2004

VERITAS NetBackup™ Professional

This product is now in End of Life status.

On 6/30/04 VERITAS NetBackup™ Professional was put into End of Life Status.

CGI-bin Laden
Monday, August 09, 2004

Had the same problems with Backupexec on NT. AFAIC, just the number of services is installed is good indication of the quality of the underlying code.

Also, DAT drives are known to be less rugged than DLT.

Since backing up to tape takes forever with today's huge drives, what about using some basic software just to perform incremental backups on removable hard drives, so you just unplug the drive to take with you at night?

Fred
Monday, August 09, 2004

Depending on your situation, you can copy your data to an EXTERNAL disk drive. Very fast. Then the drive is removed and stored.

Now I'll admit this is easier for a once a week backup than nightly.

frustrated
Monday, August 09, 2004


For only 20Gb disk is an easy winner.
Get a USB2 external disk caddy ( about $25+cost of drive)
Copy database onto disk as regularly as you require.
Have a couple of them and rotate them - take one home at the end of the week.

If the data doesn't change much look at rsync. It's a venerable unix tool that is available on windows but isn't well known.  It copies only changed parts of files and is very network efficent, you can tunnel it over ssh / vpn to a machine at home on broadband - cheap offsite backup.

Martin Beckett
Monday, August 09, 2004

I would agree that for small (< 200GB) databases HD backups are probably a win. We use several backup tools for our <100GB DB:
Sybase Replication Server -- Transactions are replicated real-time to a separate, offsite, machine, so if one box blows up the other is fine. Both machines are set up in HA with RAID disks to avoid single media failure blowing up the system.

We then backup the DB from the replicated box to a separate offsite server which also is then backed up to tape (which is removed offsite, too). So I guess that’s four locations in which the DB resides although only the replicated server(s) provide up-to-the-second recovery. The tape machine gets transact logs shipped to it “as necessary” (every 10 minutes or so) and then the tapes are only removed nightly, so theoretically if both the primary and secondary servers explode in a shower of sparks we’d be maximum of 10 minutes lagged, which is not too bad.

For databases that are sufficiently large (1000GB and up) creating multiple copies on disk is much more difficult than with tapes. As HD density increases, though, I suspect tapes will eventually die off. There’s still the nice feeling of being able to pay someone to physically move the data somewhere safe – preferably in a vault below sea level.

Captain McFly
Monday, August 09, 2004

I would very often vouch for a NAS / SAN based backup solution with lots of RAID disks inside over a tape. Having a proper RAID array negates the worry over disk failure, and synchronize with a similar setup offsite to remove the risk from fire. Of course it depends on volume of data, but in the organisations I've worked with, we've used their bandwidth overnight to transfer data out. Typically only a small amount changes daily so it is more manageable than it might at first appear.

I know of a particular organization (where I did not have any involvement in the backup solution, I just did their website) where their file server takes the whole night to do a tape backup with BackupExec. Sometimes it runs over, and at 8:30 it's still running when people arrive and want to use the system. It doesn't handle one of their particular bespoke applications very well (I don't know the intricacies of this so no idea why). Half the time BE reports a failure but the manager assures everyone that it doesn't really mean it failed, it just skipped some open files. Sure, there are test restores occasionally, but I still wouldn't have complete confidence in that system. And with a backup system, complete confidence is critical.

And yes, I know that their system is a bad example, and most tape backups are set up much better. But I have no doubt that there are many companies like that, who don't have enough in-depth knowledge of BackupExec, or the money to pay someone who does, so are just using it as best they can.

With a SAN system (assuming it just directly copies files rather than compressing) you could actually go in via explorer and look at the files. You could do test file-opens etc to check they work. Restores would be infinitely quicker. You're removing potentially the most dangerous element of the backup, and that's the format used by the backup software & tape drive. I as an admin would have much more confidence in a san system than a tape.

James U-S
Monday, August 09, 2004

(I'm not saying that SAN is necessarily the best option for everyone, but it certainly should be given more consideration. I often find that it is either overlooked or dismissed almost straight away)

James U-S
Monday, August 09, 2004

Note -- RAID only protects you if one drive decides to fail at a time.

I have seen an entire RAID-5 bite the dust at the same moment.

Flamebait Sr.
Monday, August 09, 2004

"I know of a particular organization (where I did not have any involvement in the backup solution, I just did their website) where their file server takes the whole night to do a tape backup with BackupExec. Sometimes it runs over, and at 8:30 it's still running when people arrive and want to use the system."

I've heard this story too many times!  The reality is that so many tape backups are so cumbersome and error prone, that test restores become less likely (unless mandated) and you have no idea if it works.   

My job is primarily a developer/architect - i do all this backup admin stuff because i can't afford somebody to do it for me, and i fully admit that i don't focus on it enough.  If I had a network admin, I'd have them doing this regularly.  :(

Fed up with tape backups
Monday, August 09, 2004

Most of the comments above seem to be referring to crashes only. What if some data is deleted/modified by mistake and it comes to notice only after several days? If you are backing to tape, its relatively easy to revert to a time close to when the data was deleted/modified. It is normal to have 2-3 week tape cycles along with weekly/fortnightly/monthly tapes. We use Legato Networker in our office. Its not at all user friendly but is several times faster than Backup Exec.

Also auditors are very particular about backups being stored offsite and its relatively easy to transfer tapes to/from offsite storage.

Kedar
Tuesday, August 10, 2004

Use the buildin backup of SQL Server to backup the DB's to disk, then backup the backup to a medium of your choice. for small volume (one backup fits on one disk), I'd do HD's. We used to do tape, but there was just too much tapedrive HW failiure and speeds were awfull.

Just me (Sir to you)
Tuesday, August 10, 2004

Raid5 is rarely the answer, it seems that random failures of the raid system are more common than random failures of the drives.

I've had power supply faults burn all drives on a channel

Drives which fail pinning the scsi bus and leaving you to juggle drives in and out try to work out which one is bad while the raid tries to rebuild on you at the same time.

Had drives in two separate raid systems fail at the same time. Bought at the same time from the same maker - drives out of the same batch.

Remember if your data compresses well use a compressed fs on the backup drive and you can use slower cheaper disks in the backup system so it's not too expensive to backup all your disk space onto removeable drives.

Another advantage of disk over tape - even if the backup disks are slow you can run off them while recovering the main system - with tape you just have to wait.

Martin Beckett
Tuesday, August 10, 2004

Why not send the delta over the net to a safe place?

Christer Nilsson
Wednesday, August 11, 2004

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