Best utilization of USB HD for B2D

[JB_Welna]

I am using Backup Exec 2010 R2 to backup an SBS 2008 server. We are utilizing 3 USB hard drives as media, compression, and encryption. We are rotating the USB drives daily. The backup job writes to a drive pool that contains the 3 USB hard drives. Backups are done 7 days a week (people work remotely), although often no one is there Saturday or Sunday to change the drives.

I have been trying to optimize BE's use of disk space on the USB HDs. I had hoped that the drives would fill up to the threshold (50GB of a 1TB drive), and then overwrite the oldest backup sets. I don't seem to be able to hit on the combination of overwrite/append that allows me to do this. The job has been set to overwrite scratch media before recylable media (in the hope that it would use free disk space before overwriting existing backup sets), but this doesn't seem to work. It appears that the overwrite period is controlling everything, in that once an existing backup becomes overwritable, it is overwritten, as opposed to using free space on the disk. I have the append set to infinite, and the backup file set to 125GB ( about 85% of the size of the current backup).

Is what I am trying to do possible? Is it a bad idea (disk fragmentation)?

At this point, it looks as though the best I can do is set the append period to 5/7 of the total number of backups I can fit on 3 drives (ie leaving 2/7 for Saturday and Sunday when no one might be on site). That leaves about 30% of the drive unused, including the threshold. The client is sqwuaking that he's not getting the drive space he payed for on the backup drives.

Thanks!

Joe Welna

[Ken_Putnam]

First, for Disk jobs, I recommend all Overwrite, no Append

Yes, if you want to fill the drive up and then overwrite, select the "use scratch media before overwriteable media in the target media set"   This should cause BackupExec to create new BKF files until the disk is full.  Since these are dedicated backup disks (right?) I'd set the reserve to 0 - None. 

How long do you want to ensure that data is kept?  One week, two weeks?  Set an OPP for the appropriate media sets. ( I have seen some really strange things when Overwrite is set to 0)

[pkh]

What you are experiencing is the expected behaviour.  You don't really want to hit the threshold.  If you do, your job will be paused until you clear some space on the harddisk by deleting some files on it.  You should be avoiding it like the plague.

You are already doing the right thing by using the OPP to maximise the use of your harddisk, just don't try to hit the threshold.  Give BE a comfortable margin.

[JB_Welna]

Do I understand correctly that you guys disagree???

PKH,

Do you mean that if I set the job to overwrite scratch before recyclable, set overwrite protection to none, set  append to infinite, and threshold to 50GB, BE will always leave about 30% of the USB drive free? I'm not saying that this is what I'm going to do (I will use OPP), but I did try that and it is what seemed to happen.

Would this be different if I set append to off and the threshold to 0, as Ken suggested in the first reply? Does setting threshold to 0 prevent the job from pausing once the disk is full and force overwrite of the oldest job?

Thanks again.

Joe Welna

[Ken_Putnam]

Again, for disk based jobs, I recommend that ALL jobs specify Overwrite, not Append  (since all BKF files in an "append famuily" share a common OPP, which is reset each time a new one is closed, meaning that NONE of them ever expire.)

And, again, I would recomment a Global Overwrite option of Partial or Full and a media set OPP of 1 hr

If you get BE to start overwriting as you want, then there is no reason to have a reserve on a disk used only for B2D.  Setting the reserve to 0 means that all space on the drive is available for BE data.  If you have other data on the drive (not recommended) them setting the reserve means that BackupExec will leave space for the other data.

[JB_Welna]

OK, I'll try that.  I know you've personally given me great answers to my previous questions. I was just a little surprised that the next post seemed at odds, but perhaps I misunderstood.

Thanks

Joe Welna

[pkh]

You must understand how the threshold parameter work.  When you set the threshold parameter to say 50GB, BE will stop when the free disk space is at 50GB.  You will be prompted to free up some disk space by deleting some files on the disk before the job will continue.  BE will not, as you imagine, go and overwrite some other file.  For example, your max .bkf file size is 30GB, your threshold is 50GB, the free disk space when you start your job is 60GB.  Since you say overwrite scratch first, BE will create a new file and start writing.  After writing 10GB, it will hit the 50GB free space threshold and it will stop.  It will not go and overwrite your other .bkf files even though they are overwriteable.  You would need to delete these files manually to free up space before the job can continue.

If you set the threshold to 0, as Ken suggests then you would be just delaying the inevitable.  In the above example, BE will write 60GB before it stops and prompt you to free up disk space.

[JB_Welna]

I think I understand now ...

PKH, are you saying that I should disable the threshold (as opposed to setting it to 0) and the drive will fill up and overwrite as Ken says is possible? Or should I just leave a comfortable margin on the disk (say 30%) and try to optimize the OPP to fit within that margin?

Is there any difference in "threshold" and "reserve", as seen in older versions of BE's B2D settings (like version 8.5)?

I'm trying Ken's settings currently to see if they work before committing anything to the production environment.

Thanks again to both of you for your knowledgeable input. I hope I didn't stir the pot too much.

Joe

[JB_Welna]

Well, maybe I don't understand ...

Ken, I've tried your settings, and they don't seem to work as you suggest they should.

Global overwrite is partial. Global is set to overwrite scratch before recyclable. Job is set to overwrite, not append. Threshold for B2D folder is disabled. Overwrite period for media set is 3 hrs.

I'm still not filling up the disk (about 25% remains free), but overwriting the oldest backup sets.

Am I still doing something wrong? Could backup sets created with other settings be screwing up the whole process? (ie do I need to start with a fresh B2D folder with all settings correct from the start for it to work?)

Thanks

Joe Welna