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Overwrite/Append Help

So I need some help understanding the Overwrite/Append features. I understand the concept but for some reason I cannot get it to work the way I'd like it to.

Let me explain my strategy first (and please offer any suggestions)

I have seperate Media sets for each day of the week.

Monday - Thursday each has it's own media set with one tape with 400 Gb of space. I' am running separate jobs for each server by day. So Monday through Thursday I have 7 Differential Jobs(this will increase when I get the hang of it) run each night along with a Full Backup of the media server (seperate tape and job)

The problem I' am having is that when a job starts i starts from square one, so when the first job starts and finishes it writes fine, but when the second job starts it overwrites the previous job and so on. I know this is an append problem but the main thing here is I do not want the tapes to fill up.


What I'd like to see happen is Mondays Differentials all complete on 1 tape and that tape is protected until next monday when the job is scheduled to run again and the same for Tues - Thurs as these are jobs that will continue to run week to week.


Questions.

Do I need a bigger tape? I have 800 Gb tapes that I use for the Full backups but I could add 1 400 and 1 800 to make 1.2 TB per Media set for each day of the week. I have alot of servers to backup.

Settings

Here are my Global settings.

Under my media settings I have it set to Partial with no prompt. And no Backup-to-disk folder is created.

I have each job as Overwrite media. (should this be on Append and overwrite if no appendable media is found?) And each job is statically assigned to each tape.

I have each Differential Job as "Differential - Using Archive Bit (do not reset archive bit)"

Please let me know if you need anymore information Smiley Happy

Thanks!

18 Replies

What is the Append period and

What is the Append period and the Overwrite period on the media sets that u have configured?

 

An explanation of the "Overwrite Protection Period" and the "Append Period"

http://www.symantec.com/docs/TECH5459

Example : If the Append Period=5 days and Overwrite Protection Period =1 day

All the media associated with this media set will append for 5 days and will be protected for 1 day and after that the media will be an overwritable media.

So if the Append period is 5

So if the Append period is 5 days and the Overwrite is 1 day, the media will be protected for 1 day... Does this mean that you get 5 days of backup appended to the tape but in one day it will overwrite from the  beggining  of the tape?

Yes, The tape will be

Yes,

The tape will be appended for 5 days and as the append period is over the overwrite protection starts and it will be overwrite protected for 1 day.

The overwrite protection period AFTER the append period is over.

Ahh so If I set my settings

Ahh so If I set my settings to the settings your suggesting it should work. what if the tape fills up?

The overwrite protection

The overwrite protection period starts when the append period is over. So the media can be appened till 5 days and then it would be protected for 1 day

The overwrirte protection

The overwrite protection actually starts the last time the tape is written to

In the case of a tape filling up, the time if fills up is when the overwrite protection starts.

In the case of a tape that is appended and is not full it will start from the the end of the last append job to run to the tape  (which is where Dev T's slightly incorrect understanding has come from)

However if you want ta Monday tape to only be used on a Monday then you should l perhaps consider a 12 hour append period and a 6 day overwrite (assuming your 7 differential jobs finish in 12 hours)

Also if you want to make sure that a specific slot in the library always contains the tape used on a Monday - then you need to Partition the slots in the library and then target the Monday job to the Monday Partition (there are other concerns when doing this however as jobs will fial if there is not enough space available in a partition, a partion can contain more than one slot)

 

 

My tape is only 21 Gigs

My tape is only 21 Gigs filled out of 400  and it says this

Overwrite settings are as follows (this is for my Hourly incrementals)

Overwrite protection 9 Hours

Append 1 day

Please insert overwritable media into the robotic library using the import command.

Overwritable media includes scratch, blank, and recyclable media. Please note that depending on the current Media Overwrite Protection setting, imported and allocated media may be overwritable as well. Consult the online help for more information on overwritable media.

Was that tape first used

Was that tape first used yesterday - as if it was then it wil now be overwrite protected for 9 hours from the last append.

If you are using a single

If you are using a single TAPE for a day you should configure the Append period for 10 to 12 hours and the overwrite period by 6 days so after the
Monday's backup the TAPE will be overwrite protected and the same tape will be ready for next Monday as the Overwrite protection period is over.

Ahh yes Colin it is used

Ahh yes Colin it is used every day from 6 AM till 6 PM

So I should set the overwrite protection period lower? Calculate the time from the last append to the 1st append right?

Since Append starts when the

Since Append starts when the first data is written to the tape, one day after that, you can no longer append to the tape, and BackupExec will prompt you for an overwriteable tape

Append only applies to the first tape used by a job.  If that one fills up, then all other tapes will be Overwrite. 

Similarly, if BackupExec cannot find an appendable tape in the target media set, and cannot find a scratch/overwriteable tape, it will prompt you for an Overwritable tape

As you said that 1 day 1 tape

As you said that 1 day 1 tape is used, so I would suggest you to configure the Append=10 hours and overwrite=6 days

I guess what I'm looking to

I guess what I'm looking to do Ken is have an hourly incremental on my media server that appends the data for one whole day then restarts the next day.

Start time is 7 AM to 6 PM.

Last write is at 6:30 PM so from then until 7 AM is the overwrite protection window. I should set this alittle lower as to allow some leeway for the times.
can you verify this?

No. Overwrite starts when the

No.

Overwrite starts when the last data is written to the tape

Append starts when the first data is written to the tape.  with an APP of one day, one day after that, you can no longer append to the tape, and BackupExec will prompt you for an overwriteable tape

Append only applies to the first tape used by a job.  If that one fills up, then all other tapes will be Overwrite. 

Similarly, if BackupExec cannot find an appendable tape in the target media set, and cannot find a scratch/overwriteable tape, it will prompt you for an Overwritable tape

I've found that when you

I've found that when you change the policys Overwrite/Append settings and you have one qued you have to cancel the job before the error will go away.
 

Here is what I'm trying.

Append = 10 Hours

Overwrite = 20 Hours


will this work?


 

Here is what I'm

Here is what I'm trying.

Append = 10 Hours

Overwrite = 20 Hours

will this work?

After 30 hours from the backup, the tape will be ready for overwriting. If you want to keep the tape for more time increase the overwrite period. I believe that you are using a single tape for a day and you want to use the same tape for that day the next week.

If the last append ends at

If the last append ends at 18:30, and you want the next day's data to start writing at 0700, you would need to set the OPP to 11.5 hours  (I'd use 11, just in case the evening job runs long for whatever reason)

@jake213 - I think you have

@jake213 - I think you have an overly complicated scheme and is going around in circles.

When it comes to AP and OPP, just remember these two things

1) AP starts when the first data is written to the media (disk or tape).  The end of the AP does not change with subsequent writes to the media.

2) OPP starts at the end of the job that last write to the tape.  The end of the OPP will change as data get written to the media.

You are using a tape library.  If you are not removing the tapes from your library on a regular basis to bring to off-site, then you should not be overly concern about which tape is used and how many tapes are used each day.  The library can manage all these and you should not be managing your tapes.  Let BE and the library do what they do best, i.e., manage your tapes.  Read my article on this subject.

https://www-secure.symantec.com/connect/articles/must-mondays-backup-be-monday-tape

I believe you want to utilitse as much space as possible on your tapes by putting all your daily backups during weekdays onto one tape and then re-use the tape the next week.  If you are not concern about which day's data go onto which tape.  You can make do with just 1 media set with OPP = 6 days and AP = 23 hours.  Why these settings?  The AP = 23 hours is so that your daily job can append to whichever tape that is used for the day and by the next day, the tape cannot be appended to by the next  day's jobs.  The OPP = 6 days is so that the tape is overwriteable the following week.  If you set the OPP to 1 week, then the tape would not be overwriteable the following week.  Remember OPP starts from the end of the last job that writes to the tape,   If your daily jobs starts at 1 a.m. and the last job ends at 8 a.m. then the Monday's tape would only be overwriteable at 8 a.m. the following Monday and would not be overwriteable when your first Monday job starts at 1 a.m.  With this scheme, you first daily job should specify Overwrite and the rest of the jobs specify Append, then Overwrite.

If you want to make things complicated and use either partitions or separate media sets for each day, you can do so, but each of the media sets should still have OPP = 6 days and AP = 23 hrs.

Regardless of how many media sets you use, do make sure that you have sufficient spare tapes in your library so that when your designated tape is full and it will at some point, BE can have something to write to.

When you are changing either your AP or OPP settings, the effect of the change is immediate.  This means that if you extend the OPP by 2 hours, whatever tapes in the media set will be further protected for another 2 hours.  Always check the status of the tape before your jobs start to make sure they are what you expect.  You can do so by clicking on the tape in the Media tab.  This will save you the trouble of understanding why your job failed because there is overwriteable tape.  You can stop this check only when things are in a steady state.