Tape Drive Cleaning frequency

I have a new Dell Powervault 110T DLT tape drive.  Full backups once a week are about 40 GB, incremental backups daily are about 12 GB. This drive has been in service for about 1.5-2 months and the cleaning light just came on.

This lead to a discussion with a Dell technician who tried to tell me that the drive should be cleaned after every 4-8 hours use.  Bear in mind that the full backup takes about 15 hours.  I said that according to his logic that I needed to be cleaning the drive after every use.  He said "sure plenty Dell customers clean them that often".

I must only know the lazy admins because I've never heard of anyone cleaning their drives after every use.  In fact, I know people who don't clean the drive until they get read errors.

This led me to searching for recommendations.  I found widely varying and sometimes conflicting recommendations.  Can anyone point to authoritative sources of info for this and other drive types?
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QuetzalAsked:
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sirbountyConnect With a Mentor Commented:
I wasn't referring to the cost of the cleaning tapes.  It's always been my understanding that scheduled cleanings caused unnecessary head wear on the drive.

We've used the compaq DLT drives ranging from 15/30 on up to 40/80 and the library models from 35/70s on up to the SuperDLT MSL5026 (110/220) series.
I'd say there has to be a total of 350 or more DLT units in our enterprise at this moment.  We don't perform any scheduled cleanings on these drives.
The only time we do run cleaning jobs is when the software or hardware requests it or we've experienced a CRC error on the backup.

Our DBAR procedures include scheduled restores however, of which the success rate is about 94%.  And I would say the failures come from faulty tapes (of which we do receive a small percentage of), not from uncleaned drive heads.
Perhaps the missing link is the way the tapes are stored/handled and the environment the equipment is in...
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sirbountyCommented:
That's ludicrous.  I'll see if I can find supporting documentation - but our Compaq rep (several of them actually) state taht you should NOT clean unless the indicator (hardware or software) denotes that it's necessary, or in the course of troubleshooting a suspicious job failure (CRC)...
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QuetzalAuthor Commented:
That's what I thought too, but he made the "plenty people do" remark in a way that made me feel like I must be some kind of dork for not knowing that.
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sirbountyCommented:
A-ha!  Your Dell tech is referencing DAT tapes apparently...
See: http://h18000.www1.hp.com/support/techpubs/whitepapers/244a0996_ch5.html#link1 on the 'recommended cleaning' section.

So, follow his 'plenty people do' with 'O yea, on DLT tapes or DAT tapes?'
Then to be mean, if you want say "So, where'd you go to school again?"  LOL


This is from an HP forum -by an HP rep apparently...but I'll keep looking:

>>Please use caution with this last advice: DLT drives are not supposed to be cleaned proactively, as this wears the heads of the drive unnecessarily. DLT drives are only supposed to be cleaned if the drive requests such an action.<<
ref:http://forums1.itrc.hp.com/service/forums/questionanswer.do?threadId=32865
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QuetzalAuthor Commented:
lol, I almost don't remember those "big" 2 GB tapes any more.  WRT DLT and SDLT, most of the refs I found agree with your last bit, however, I found one site recommending regular backups for such drives.
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sirbountyCommented:
I'd like to see that then...I've been working with DLTs for hmmm over 6 years at least and this has always been the consensus...

>>Using DLT Cleaning Cartridges
DLT drives should only be cleaned if the clean drive icon displays on the
tape library or autoloader status bar. Only use the appropriate DLT
cleaning cartridges and follow the instructions in your tape library or
autoloader user’s guide. In general, replace DLT cleaning cartridges after
twenty uses. Marking the label on the cleaning cartridge after each use
will help you keep track of the number of uses.
CAUTION Excessive use of the cleaning cartridge can cause unnecessary wear on
the drive head. The tape library or autoloader front panel will display a
message when the DLT cleaning cartridge needs to be replaced.<<

ref: http://h200005.www2.hp.com/bc/docs/support/SupportManual/lpg28701/lpg28701.pdf
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sirbountyCommented:
Not to mention that the 'life' of a DLT cleaning cartridge is 20 uses....
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5t0rmUKCommented:
We have several tape backup systems in place including the model that you mention.

The cleaning tapes are run every Friday just before performing the weekly backup, this process has been performed now on some tape drives that are over 2 years old without a single byte of data lost in this time.

The Dell engineer sounds very much like the HP one that recently visited a clients site and told him that his plotter was knackered and would cost over £1000 to repair, bear in mind after a 30min visit by me this unit is now funtioning perfectly once again !!

Like i said once per week is more than enough.  Anymore is overkill.

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sirbountyCommented:
Thanx for the post 5t0rmUK.
My only concern would be 'how much longer would the life of your DLT drive be, if you didn't run weekly cleaning job'?

I'd imagine that if you placed two identical drives side by side and ran a weekly cleaning on one and only a periodic cleaning on the other - the second one would last longer, and thus provide more bang for the buck (so to speak)....
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5t0rmUKConnect With a Mentor Commented:
Sirbounty,

A customer of ours did exactly what you are saying, they used the cleaning tape every couple of months, all data backed up fine and verified fine, until they come to actually restore the data a few months down the line !!

By not cleaning the drive, crap & particles will start to build up on the tapes themselves rendering them useless after a few months use, so by saving on the cleaning tapes you are losing on the media tapes when they fail to work.

To be perfectly honest the cleaning process is not going to make the DLT last any longer and in my opinion is not beneficial to the longetivity of the hardware.

Do not forget this is a BACKUP OF ALL YOUR VITAL DATA, cost really should not be an issue when it comes to backups, believe me I know when I never backed up, my raid array failed and I lost the whole of my yearly accounts.

A few £ / $ saved in the shortrun by not cleaning weekly should not be an issue, the safety and integrity of your data should be.

 
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QuetzalAuthor Commented:
sirbounty, 5t0rmUK: Thank you both for your replies.  I'd say that you are each reflective of the conflicting recommendations I've seen.  I don't feel like such a dork now, but I can see that there are probably lots of people in either camp.  I would say that based on sirbounty's experiences, waiting until the hardware says "clean me" or getting a CRC error on backup is an acceptable strategy with acceptable restore reliability.  Scheduled restores are a key part of any backup strategy.

Because you've both given me the benefit of your experience, I am splitting the points.
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5t0rmUKCommented:
Quetzal thankyou very much for the points.  Like you mention there are no real hard and fast rules.

Some of our clients like to clean the tape drives weekly, some prefer monthly, but at the end of the day it is entirely up to the customer / end user.  I myself think that anything other than 100% in backing up and restoration is not acceptable, whereas others  are more than happy with 95% or less.

One of our main customers has Raid 5 in place with nightly tape backup and also a full file backup to another server..Overkill ??  not for them it isn't as they solely rely on I.T. for the day to day running of the business.

This is one of those topics that could be debated for quite a while !!

Thanks again for the points, and congrats to sirbounty also for sharing in the spoils with me ;-)

Mike.
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