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BE15 Not using all the Tapes to back up

Hi,

We have two LTO6 tape drives (4 tapes in total 6-1 to 6-4). We run a full backup to disk, then a dup to tape. On the days when i do a full backup, I inventory the tapes then erase them so they are empty. I have set up the jobs to use one storage pool and the LTO6 drives to use as the backup needs to (not allocated to a drive as such).

Came in this morning and 6-1 tape was out of the drive and BE requesting insert new tape. The 6-1 tape was full but the drive 6-2 had 2.01TB (out of 2.27TB), but 6-3 and 6-4 had hardly been touched?

Whey would BE not use the other available tapes? Have made sure the drives are available in device manager etc.

Thanks in advance.

5 Replies

Re: BE15 Not using all the Tapes to back up

Once Backup Exec chooses a tape device/drive (within a pool) for a job, then that job will only be able to use that drive.

We then look at the tape in that drive to confirm suitability against the media protection settings and use it.

If we either cannot use the tape, or use it and then fill it, we eject the tape and ask for a new tape to be inserted in the same drive, the job will NOT flow to a different drive, hence you will see an ejected tape and a media insert request

We did used to have the ability to allow a job to flow between tape drives and this was known as a Cacaded Drive Pool. However we discontinued support for this ability around 9 years ago.

You really need a tape library and not stand alone drives for your scenario - or create two jobs and split the selection list  (which may be able to run in parallel so could have the advantage of saving time)

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If you are using a library then apologies this was not clear from your query

Re: BE15 Not using all the Tapes to back up

Hi Colin, You are correct we are not using a tape library.

Thanks for your help but a question regarding Storage Device Pools. Why does BE15 give you the option to create a storage device pool, and then let the application use the available devices, in this example the LTO6 tapes?

If i open a job and click Edit, then Storage, within the drop down i have LTO6 (4 devices are in this pool), and also the other options of Any Disk Storage, Any tape cartridge storage. Am i wrong to think that this should use the next available tape?

In the following Veritas website it states "When you send a job to specific storage devices, Backup Exec cannot automatically route the job to the next available storage device. When you submit a backup job to a storage device pool, by default the job is sent to the first available storage device in that pool. As other jobs are created and started, they can run concurrently on other storage devices in the storage device pool. "

The above line "as other jobs..." if i am reading it wrong, indicates that it should use the next available tape within the storage pool. If this is not the case then why give me the option to put all of my LTO6 drives within one storage pool?

Under the Storage tab within BE15, if i double click my LTO6 storage, it lists all of my drives within the "Storage Devices that belong to the pool" - so my Drives 6-1 to 6-4 are listed. If a job runs and startes to backup on 6-1, and completes, then tries to backup the next job on any available tapes within the same storage pool, (because its in the same storage pool), why doesn't it?

How then, if any, can I make B15 use all of the tapes within the same storage pool.

Thank you again for your help.

Re: BE15 Not using all the Tapes to back up

As per "When you submit a backup job to a storage device pool, by default the job is sent to the first available storage device in that pool." "

We use the next available device in the pool as a decision taken at the start of the job ONLY so we do meet that description as the single Job has been assigned to the next device as it starts.

As per "As other jobs are created and started, they can run concurrently on other storage devices in the storage device pool. "

If you actually create multiple jobs and start them in parallel (say starts times only 5 mins apart) you should see as many jobs start as you have available drives to run them on. With any extra jobs above the mnumber of drives going queued. Hence we meet that bit iof the description .

What we don't do is allow a single job to fill a tape in one drive and then move over to using a tape in the other drive. Once a tape is full in that first drive (in the middle of a single job) someone has to insert another tape into that drive for that job to continue.

Tape Device Pools at there to load balance (or availability balance) at the start of jobs only, they do not allow spanning (cacading)  between devices mid-job.

So the best practice / recommended solution is invest in a library if your daily jobs are likely to use more than 1 tape, however if you must use multiple stand alone drives then the only option is to split the selections into separate jobs so that no single job fills a tape.

Couple of extra points:

If you append to tapes instead of overwriting them, then the media insert request for filing the tape will happen earlier in the job, so best way to miminuze this effect is to overwrite tapes at start of jobs (which you were doing anyway by erasing the tapes)

You can't really plan to use 100% capacity of any tapes if not using a library unless you are willing to have someone onsite to insert changed tapes at required moments

For info : I think we are working on an edge conditon where if one drive is asking for a media insert other jobs that could use the other drives will not start until request has been  acknowledged. I believe we will have a fix for that in a future update (when released the fix will be for for current BE versions not older ones) I am not sure if you experienced anything related to this, however if you did have multiple jobs where a job was scheduled to start at a later time, and this start time was then after one of your earlier jobs got stuck asking for a media insert then that later job probably won't start. It is therefore possible that an effect relating to this problem would stop you using all your devices.

Re: BE15 Not using all the Tapes to back up

Hi Colin,

Thank you for clarifying this for me and your help. Just to confirm regarding my question I do understand that a job cannot span a tape, from one tape to another. But I was asking if multiple jobs can indeed utilize the available tapes within the pool itself. 

As you can see from the image, Drive 6-1 is indeed full, due to different jobs being written to that tape. But Drive 4-2, 4-4, 6-3 and 6-4 have hardly been touched.

Sorry if I didn't make myself clear.

Thanks again in advance.

Re: BE15 Not using all the Tapes to back up

Yes multiple jobs can use multiple tapes - except for the problem I described - basically as soon as one drive gets stuck requesting a media insert, any new jobs that try to start probably will not start. This is due to the stuck job potentially being holding onto the device and media control (we know this has can have a negative effect in multi-drive libraries, not 100% sure of effect on stand alone drives) . Any jobs that are already running would continue to run.  We are intending to correct this behaviour, but probably only in the latest version of BE

Looking at your picture it looks like you have a CASO setup with 2 stand alone drives per backup server, I can't see what your jobs are like but assuming this is because you have five sites, I guess you want to keep jobs within the sites, so you can only run 2 jobs at a time per site. if any site needs to run more than 2 jobs, then you would need to make sure that the first 2 jobs (per site) to start are overwrite jobs and any later jobs are append jobs using the same media set as the first jobs. If any of the later jobs try to start as an overwrite, or use a different media set then that would also result in tapes being ejected and requests for overwritable media.

Note: I am not sure if the affect of one job requesting media could possibly lock out all of the drives in a CASO setup or only those local to each server, as CASO setups have centralized device and media control as well as centralized job control.