Error - Not appendable (Media full)
Ok I am not going to read all your exact points as this thread is too long. However I will explain a few key points about how it works
1) If your tapes are both overwritable and appendable when a job starts and if the job is set to use append at start then it will append to the tape. Either change your job start settings or your media set append period to avoid this.
2) As soon as new data is written to a tape (either an append or an overwrite) it will move the overwrite protection back to whatever the media set states. In other words the overwrite period is not fixed to the first overwrite like the append period is but will move.
3) The overwrite protection period is always calculated from the last write to the tape (so the end of a job not the beginning)
4) If a job fills a tape in the middle then the tape will be ejected (from a single/stand alone tape drive) or returned to a slot ( for a library ) and a new overwritable tape will be requested. Note for an eject in a stand alone drive, the cartridge will still be resting physically in the drive but will be in an ejected state that will require someone to take action to change.
5) If an overwritable tape cannot be found (no tape in drive for stand alone drive or no overwritable tape in any library slots) then you will receive an insert media alert and the job will sit waiting.
6) We can only append to the first tape used by a job, subsequent tapes chosen as each tape fills up MUST be overwrittten
7) An overwrite of any media is a complete overwrite/erase of the media no matter how many backup sets are contained in the media - in other words you cannot overwrite just the first backup set held on a tape.
7a) I suspect (but have not tested this) that because of point 7, we block the overwriting of a tape that was appended to at the start of the job, that ended up filling the tape, to avoid a "swallow your own tail scenario" and in effect corrupting your own backup. I would expect this block to occur even if Overwrite Protection is set to "None" on the media server although as stated this might need a test to validate.
8) Whether or not a tape can be overwritten depends on it's protection timings when the backup job starts. When you come in the next morning and realize your overnight backup job is awaiting a tape, the status of the tape at 09:00 that morning will not reflect the status at 20:00 the night before and will mean that wrong facts are being used to understand whether or not you had overwritable media available.
9) Once a job has decided it cannot use a tape it will not suddenly start using that tape just because the job has sat waiting for long enough for the tape to become overwriteable. It is possible (again I have not tested this) that acknowledging the alert in the BE console after the tape has become overwritable would use the tape or the job might continue to ask for a different tape.
10) Whilst the admin guide is a bit overwhelming, the one chapter I recommend all customers using tapes spends time to understand is the one relating to overwriting and append on tape - which in the BE 2012 Admin Guide is Chapter 13, and the section entitled "About tape and disk cartidge media". Pages 371 and 372 contain a couple of very useful graphics and page 378/9 provides a breakdown of how overwriteable media is chosen
11) Backup Exec will move media from one media set to another if the overwriteable media is found in a different set (see the admin guide info in point 10 for why this happens) Understanding your media management and/or partitioning the libraries can help control this.
Some general recommendations
a) Do not set Overwrite protection to none, this is a recipe for overwriting media you need too early.
b) Do not overwrite your only existing backup set before you have completely finished, successfully, creating the next backup set of the same data - if something happens duriong the backup job activity to create the second backup set you will have no backup at all rather than still having one backup to restore from. In other words set you overwrite protection to at least one day if doing daily full backups and longer than a week if doing incremental sets with one weekly full.
c) If you have too much data for one tape and are using a stand alone drive then invest in new hardware (preferably a library)
d) Again if using a stand alone drive, and primarily if appending, understand when your tape will fill up and plan to change your tape before a job is likely to fill it completely. Do not try to completely fill it and you will then avoid a job waiting all night for the next tape.
e) If you know you need to do a critical restore from tape, then slide the write protect tabs across on the tape itself. Then if something distracts you before the restore has been actioned, no accidental overwrites can occur dure to a backup job that has run.
f) If your library supports barcodes then use them, but make sure you have the correct format barcodes for your hardware
g) Keep a record out side of Backup Exec of which tapes were used on which days including whether the tapes have been sent off-site. If you don't do this and something happens to your media server you won't know which tapes are most critical to bring back and work with for a restore. Which means your DR restore will take longer.
h) We recommend not using Infinite append on a media sets as appending for ever creates an infinitely long media family that can cause issues restoring depending on the history of the media sequence within the family. A job that starts by overwriting the first tape starts a new family, a job that spans to a second tape increases the size of the existing family.
i) Do spend time to look at the blogs relating to media handling written by Symantec Connect members - as some of the members have been using versions of Backup Exec for years and have day-today ongoing experience of setting up various scenarios, their "real-world" advice on how media sets, overwriting, and appending etc work is usually a very good supplement to our own documentation.
