Storage - Media overwrite protection Level

[rcunha]

Hello,
I was looking at the options of the Storage.

On the options here I am set:
Media Overwrite protection level => Partial - protect only allocated media
Media Overwrite options => Overwrite recyclable media contained ....

It was working good with ISCSI disks, but I need to use one tape drive LTO3 to backup some files. The problem is that with this configuration: Partial + Overwrite recyclable media contained ..., the tape drive Always ask for me to put a Recyclabe Media, if the Backup Exec use the tape just one time, it is not possible to reuse the media on this drive.

I was looking at the manual:
https://www.veritas.com/content/support/en_US/doc/59226269-99535599-0/v53890943-99535599

And it Explain that is not good to turn on these options:
None - No overwrite protection + overwrite scratch media first
None - No overwrite protection + overwrite recyclable media first
Warning:
These options are not recommended because it does not protect data from being overwritten.

I think the only way to put these LTO3 Tape Drive, is to use these options, I think to change to that => "None - No overwrite protection + overwrite recyclable media first".

The question is, It is secure to enable That Option ? My backups at the ISCSI disks are affected ?

The manual said: This options is not recommended because it does not protect data from being overwritten. "I´m not sure If I have problems if I enable that Option, if the Backup Exec erase the media with backups that not expire or something like that.

[Colin_Weaver]

If you use a single tape drive then to avoid a tape insert request you have to make sure the tape you insert either:

1) if the job starts as append, there enough space remaining on the inserted tape so that the append job can run (which also requires the same media set for the job and the tape membership)

OR

2) if the job is set overwrite at start that the inserted tape is overwriteable

Any job that starts as an append and can't find an appendable tape in the same media set or any job (at all) that fills the remaining space on that tape, will then ask you to insert an overwritable tape and it is ONLY the search order for how Backup Exec decides which tape to try and overwrite that is affected by the various settings. (although with a stand alone tape drive this search order is narrowed down to is that tape that is inserted overwritable.)

If you set either of the None Options then any tape in the drive will be overwritten (meaning all existing data on it is completely destroyed)  - this is why it is classified as dangerous as you have to rely on the person changing the tapes to make sure they are not inserting a tape that is needed for longer. As far as I am aware, an append job writes some data to a tape and then fills it, and even with No protection enabled, cannot overwrite the same tape (as it would be ejected) - this is a good thing as you would be overwriting the beginning of the job with the end of the same job (and corrupting the backup set) if this was allowed.)

You are probably safer not using the None Option but instead making the individual that inserts the tapes also use the BE console to move to scratch when they have inserted the correct tape for each night. However this is your decision to make.

BTW make sure if you w\ant to re-use tapes weekly (as overwrites) that the Overwrite protection is NOT set to one week (it should be set to 6 days to allow for the length of time the job takes to run because the overwrite protection starts at the end of the previous job.  (similarly montly needs 27 days and not 1 month etc)

[rcunha]

Ok, let me see if I understand.
I know if I not enable The option NONE, backup exec protected The tapes ok.

But I use this One tape Lto3 to backup some files like 10gb Day after Day, I have space for many days, my intention is that backup exec not ejected it with The protection, I want to write Day after day until The space finish, then I change the tape, like a robotic library or physical disk.

I allocated that single drive Lto3 for keep the Backups for two weeks. And like I said, I want that it right along this time and preserv The backups with this time.
I read your explanations, but I not understand how to do it? Can You tell me.

Another question, The option NONE on media affected only tapes or it affected physical disks too? But I was scared to enable it, and Backup Exec erase the .bkf files on physical disks.

[Colin_Weaver]

OK the problem you have got with using the same tape day after day until it is full is what happens to the job that is actively running when the tape fills up?

In the case of a library we will probably find another suitable tape, but with a stand alone tape drive all we can do is ask for a another tape (having ejected the initial tape as it is full.)

The next problem is say you start with an empty tape and write the first backup to it (let's say that backup started at 20:00, ran till 01:00 the next day and uses 15% of the tape). This backup repeats every day and uses approxiately the same space every day and is appending)  After 6 days of backup 90% wil be used and the 7th backup will fill it it up, eject the first tape and ask for a different tape. The 2 week overwrite protection you have set for that tape will start at the time the tape fills up (in fact it will have started at 01:00 at the end of the first job but then moved back to 01:00 after the next job etc, until the point of time that it fills up. So now your tape with a 2 week overwrite protection can only be used about 3 weeks after it was first used, not 2. Hence Backup Exec keeps it's overwrite protection for longer than you expect

It is therefor probably a better strategy to not try to completely fill the tape but to stop using it on the last job that will fit in the remaining space. For the same 15% per day, 5 hours to run each night scenario. This would mean set your backup jobs to start as append, switch to overwrite if no appendable available and set the media set to Append period 6 days, overwrite protection period 13 days, overwrite recyclable before scratch (and makes sure whoever changes the tapes knows he /she needs to change them on a specific number of days)

Now against best practices you should probably think of this scenario

If I try to write 10 days of data onto 1 tape, what happens if have a disaster (after the 9th day's backup)  where this failure takes out my server and damages the one tape cartridge I have been writing my data to. Basically best practice for tape backups is don't write a consecutive sequence of backups to the same tape. OK I know the usual response to this is along the lines of "tapes are expensive", but is a few more tapes in your environment more costly than the data loss you might experience.

As such I would say you need to rethink your strategy to use a few more tapes (at least have 2 tapes that you change daily so consective backups are on different tapes)  and because you are using a stand alone drive, don't try to fill any one tape, instead stop using them just before they fill, keep them for 2 weeks and then overwrite them (and set appropriate append and overwrite periods to achieve this) and definitely DO NOT use the None setting for the protection of your tapes as if someone inserts the wrong tape (worse case even being a tape you need for a restore) and a backup jobs starts that tape will be overwritten

Finally the protection of disk based backup sets does not use media sets or overwrite protection periods, it is purely a time based control that uses your retention settings and the sets are deleted in the background once they expre. Please read up on Backup Exec Data Lifecycle Managemenet (DLM) for more info on this.

[rcunha]

---

@Colin_Weaver wrote:

OK the problem you have got with using the same tape day after day until it is full is what happens to the job that is actively running when the tape fills up?

In the case of a library we will probably find another suitable tape, but with a stand alone tape drive all we can do is ask for a another tape (having ejected the initial tape as it is full.)

The next problem is say you start with an empty tape and write the first backup to it (let's say that backup started at 20:00, ran till 01:00 the next day and uses 15% of the tape). This backup repeats every day and uses approxiately the same space every day and is appending)  After 6 days of backup 90% wil be used and the 7th backup will fill it it up, eject the first tape and ask for a different tape. The 2 week overwrite protection you have set for that tape will start at the time the tape fills up (in fact it will have started at 01:00 at the end of the first job but then moved back to 01:00 after the next job etc, until the point of time that it fills up. So now your tape with a 2 week overwrite protection can only be used about 3 weeks after it was first used, not 2. Hence Backup Exec keeps it's overwrite protection for longer than you expect

It is therefor probably a better strategy to not try to completely fill the tape but to stop using it on the last job that will fit in the remaining space. For the same 15% per day, 5 hours to run each night scenario. This would mean set your backup jobs to start as append, switch to overwrite if no appendable available and set the media set to Append period 6 days, overwrite protection period 13 days, overwrite recyclable before scratch (and makes sure whoever changes the tapes knows he /she needs to change them on a specific number of days)

Now against best practices you should probably think of this scenario

If I try to write 10 days of data onto 1 tape, what happens if have a disaster (after the 9th day's backup)  where this failure takes out my server and damages the one tape cartridge I have been writing my data to. Basically best practice for tape backups is don't write a consecutive sequence of backups to the same tape. OK I know the usual response to this is along the lines of "tapes are expensive", but is a few more tapes in your environment more costly than the data loss you might experience.

As such I would say you need to rethink your strategy to use a few more tapes (at least have 2 tapes that you change daily so consective backups are on different tapes)  and because you are using a stand alone drive, don't try to fill any one tape, instead stop using them just before they fill, keep them for 2 weeks and then overwrite them (and set appropriate append and overwrite periods to achieve this) and definitely DO NOT use the None setting for the protection of your tapes as if someone inserts the wrong tape (worse case even being a tape you need for a restore) and a backup jobs starts that tape will be overwritten

Finally the protection of disk based backup sets does not use media sets or overwrite protection periods, it is purely a time based control that uses your retention settings and the sets are deleted in the background once they expre. Please read up on Backup Exec Data Lifecycle Managemenet (DLM) for more info on this.

---

Ok, I understand your explanations. I Will try to use two tapes in the future.

But now, I will try to put the overwrite protection period for One Hour for test with one Tape and write backups on that day after day. My intention is that the Backups stay there until the tape is Full, Is it possible to do it ? 

"I will use one hour overwrite protection because I want that the backups run on tape write day after day."

Supose that the tape is Full, the Backup Exec ejected it or subscribe the tape with more backups if I use with the conditions that I said above ?

[Colin_Weaver]

I am worried that you do not understand a key point - an overwrite destroys all of the data on a tape  and NOT just the earliest backup set on the tape. This means you cannot start re-using the beginning of a tape and keep the data on the end of it intact - YOU MUST have more tapes to handle this.  Note: disk based bakups are different as reclaims/deletions (space recovery) does happen per backup set and not across the whole of the disk storage device. 

Yes you can write backups to the tape until it is full but we have no way to say don't write the backup as not enough space, a partial backup that fills the tape will always happen before we know the tape is full (and at that popint a second tape will be asked for

If you set a 1 hour overwrite protection and the next day's job starts as overwrite, it will destroy the data from the first job.
If you set a 1 hour overwrite protection but allow appends and start the next day's job as an append, the tape will eventually be filled up and then 1 hour after it fills it will become overwritable (so the next job after it fills will overwrite it (although the job that actually fills the tape will ask for a different tape.)

[rcunha]

I will think that a single tape, have the possibility to work like a robotic library, append backups on the tape, like that I have here.

I read your explanation, to finally understand it, if I configure this single tape with allow append and 1 hour overwrite protection, It is possible to have many backups on that ok?
But if is not allow append, the tape are overwrite and data on a tape are destroyed ok?

[Colin_Weaver · Accepted solution]

I think you need to do some tests for yourself (with backup sets you do not care about to see the effects of the different settings. )

A stand alone tape drive will never appear to work like a library - you get lots of extra choices with a libary because of the fact that there are more tapes online at the same time. That said the overwrite protection and media control do work the same - but have the ability to choose from more than just one tape, hence it looks like the functionility is different (when in reality the stand alone drive just limits all the decisions and rules to the single online tape. )

[rcunha]

---

@Colin_Weaver wrote:

I think you need to do some tests for yourself (with backup sets you do not care about to see the effects of the different settings. )

A stand alone tape drive will never appear to work like a library - you get lots of extra choices with a libary because of the fact that there are more tapes online at the same time. That said the overwrite protection and media control do work the same - but have the ability to choose from more than just one tape, hence it looks like the functionility is different (when in reality the stand alone drive just limits all the decisions and rules to the single online tape. )

---

Ok, I will try to do some tests here, and combine some options, but I have a problem with the Dell Tape Drive, I Open a Topic about It, and start to see that: https://vox.veritas.com/t5/Backup-Exec/Tape-dissapear-from-the-Library/m-p/853334#M356024