Hello! I need consultation. In Symantec Netbackup for the cleaning cartridge there is a parameter of cleaning frequency of 100 hours. Which hours mean? I use 18 tapes on which backups are writing within a month. What best value I shall set in the cleaning frequency parameter?

Personally I let the robots hadle the cleaning (ours were capable of it) - loaded a handful of clening tape and left them to it, removed old and added new as required. As far as what requests the cleaning, it is the firmware of the tape drive - it detects a decrease in performaance that will be un-noticeable to 'us' and sends out a tape alert. The library detects this (via comms between the drive and library) and then loads a cleaning tape .... or If the library cleaning is disaabled, the backup software detects the same tape alert and loads the cleaning tape. So effectivly, there is no difference between the two, only 'who' loads the tape. I guess one advantage of the backup software doing the cleaning is that way, the cleaning tapes are listed in the media, and it is slightly easier to see how many cleaning there are left - whereas you probably don't log into the libraries as often.

Best is to let the library or NBU clean the drives automativcally via the tapealerts the drives will send out when they need cleaning. Manual cleaning should NOT be used, you will either overclean or underclean the drives, both which are bad for them as you have no way of telling when the drive should be cleaned (unless you go and look at the front to see if the cleaning light is flashing). When the drive detects it needs cleaning it send a tapealert which is detected by either the library (if you have library cleaning set) of bptm in NetBackup if you let NetBackup do the cleaning.

When the library detects that it needs cleaning, it may be too late and a job may have failed due to a dirty head. There are arguments for and against manual cleaning. It all depends on your philosophy and how dirty is the environment surrounding the tape library. Personally, I schedule my library to clean itself every quarter

No, it will not be too late. The drives alert well before it gets critical. The worst thing you can do to a drive, apart from allowing it to run below it's streaming speed is manually clean it.

Is there any evidence to clean every quarter? Is that too often? Is that not often enough? Even if it does suit you pkh, its highly unlikely to suit anyone else. IP: If you can ie your drives support it, let tapealert deal with it. Proven evidence based and not "too late". Jim

Consult your hardware manufacturer for maintenance information. Some libraries handle this automatically. Each model is different. This is why I do not recommend using Netbackup to schedule cleaning. It's a feature that should only be used by people who don't have cleaning functions in their robots. Like standalone drives.

Optimal the cleaning frequency

13 Replies

mph999
Level 6
10 years ago
Best is to let the library or NBU clean the drives automativcally via the tapealerts the drives will send out when they need cleaning.

Manual cleaning should NOT be used, you will either overclean or underclean the drives, both which are bad for them as you have no way of telling when the drive should be cleaned (unless you go and look at the front to see if the cleaning light is flashing).

When the drive detects it needs cleaning it send a tapealert which is detected by either the library (if you have library cleaning set) of bptm in NetBackup if you let NetBackup do the cleaning.
pkh
Moderator
10 years ago
When the library detects that it needs cleaning, it may be too late and a job may have failed due to a dirty head. There are arguments for and against manual cleaning. It all depends on your philosophy and how dirty is the environment surrounding the tape library. Personally, I schedule my library to clean itself every quarter
mph999
Level 6
10 years ago
No, it will not be too late.

The drives alert well before it gets critical.

The worst thing you can do to a drive, apart from allowing it to run below it's streaming speed is manually clean it.
jim_dalton
Level 6
10 years ago
Is there any evidence to clean every quarter? Is that too often? Is that not often enough? Even if it does suit you pkh, its highly unlikely to suit anyone else.

IP: If you can ie your drives support it, let tapealert deal with it. Proven evidence based and not "too late".

Jim
INT_RND
Level 6
10 years ago
Consult your hardware manufacturer for maintenance information. Some libraries handle this automatically. Each model is different. This is why I do not recommend using Netbackup to schedule cleaning. It's a feature that should only be used by people who don't have cleaning functions in their robots. Like standalone drives.
mph999
Level 6
10 years ago
Personally I let the robots hadle the cleaning (ours were capable of it) - loaded a handful of clening tape and left them to it, removed old and added new as required. As far as what requests the cleaning, it is the firmware of the tape drive - it detects a decrease in performaance that will be un-noticeable to 'us' and sends out a tape alert. The library detects this (via comms between the drive and library) and then loads a cleaning tape .... or If the library cleaning is disaabled, the backup software detects the same tape alert and loads the cleaning tape. So effectivly, there is no difference between the two, only 'who' loads the tape. I guess one advantage of the backup software doing the cleaning is that way, the cleaning tapes are listed in the media, and it is slightly easier to see how many cleaning there are left - whereas you probably don't log into the libraries as often.
pkh
Moderator
10 years ago
If you read my post carefully, you would see that cleaning once a quarter is my personal preference. I did not say that there is any evidence and that this should be adopted by anyone. As I said earlier, I do not want my job to fail due to a dirty tape head and this is a precautionary measure that I have taken.

What is your evidence that support your recommendation to let the tape alert do the cleaning and that this is not too late?
mph999
Level 6
10 years ago

Regarding the effects of overcleaning ...

In a previous position I spent quite a lot of time working with Imation (they make tapes) over in their lab in Germany - where they would analyse tape / drive failures amongst other things, for example by putting them under a electron microscope - so we are talking about real experts who actually knew a lot about tapes/ drive - most of them were material scientists if I remember correctly. They told me .. and what's more, they could prove the effects by showing me.

And in regards to the auto cleaning not being too late - I've worked in backups for around 11 years now, about 8 of those here at Symantec where I happen to be invoved in the majority of tape/ library calls worked on in the UK - I've done literally hundreds and I've not once seen a tape drive need cleaning manually because the automation has failed to clean in time.
ipmanyak
Level 5
10 years ago
I read In document http://en.wikipedia.org/wiki/Linear_Tape-Open

that service life of tapes of about 200 full cycles of record or 16.000 passes for LTO-5. My 18 tapes are now written 2 times a month, in a year * 12=24 times. In operation of 5 years = 120 full cycles of record.

Earlier the size of backups on a tape was 1.3-.1.4 Tb, and now 1-1.2 Tb. Whether it means that quality of tapes worsened and it is time to change them?

I use HP ULTRUIM 3280, it is not library and have only one tape slot.

In Symantec NBU for this tape drive now is 100 hours in the frequency parameter. Is it enough in my case?
jim_dalton
Level 6
10 years ago
Exactly mph999, int_rnd.