I would also suggest checking LTO2 tape drivers.

We had a similar problem here (tapes being prematurely marked full) and
it was the tape drivers installed on the server. The IBM LTO2 Tape
Drives are (according to ADIC and EMC) Notorious for having driver
issues of late. /ALE

//SIGNED//
Eddie Albert, Contractor, AFRPA CIO/IT
(703) 696-5509 

> -----Original Message-----
> From: Legato NetWorker discussion 
> [mailto:NETWORKER AT LISTSERV.TEMPLE DOT EDU] On Behalf Of Greggs, Dana
> Sent: Friday, March 24, 2006 2:24 PM
> To: NETWORKER AT LISTSERV.TEMPLE DOT EDU
> Subject: Re: [Networker] Networker Newbie
> 
> When I encounter tapes that are marked as full when the 
> amount backed up is less than the tapes native capacity, then 
> there are several things I
> suspect:
> 
> 1.) Slow write rate due to slow backup push from clients 
> (bottleneck could be load, not enough bandwidth, network 
> traffic, etc) or slow network interface on backup server. If 
> you are using copper over Ethernet than at best you will get 
> from 10MB to 35MB throughput. Because of hardware compression 
> the pipe from Ethernet to SCSI funnels open. I average 40MB/s 
> write speed and have sustained 50-60MB/s write speeds on 
> backups jobs of clients that are using GHz adapters.
> 
> 2.) Not enough data is being pushed to tape. LTO is a 
> streaming technology.  Data is written in a linear fashion 
> forward.  If you can push enough data to tape to keep it from 
> "shoe shining" or "backhitch"
> which is the term applied to the process of tape drives 
> having to slow down, stop, write file mark; start, look for 
> correct position on tape (wind forward and wind backward 
> until the correct file mark is found) and continue repeating 
> this process over the course of backup. This can cause drive 
> head damage and it definitely damages tapes. Networker being 
> the intelligent backup product that it is senses this and 
> will mark a tape as full to prevent you from using it.
> 
> 3.) Damaged tapes due to physical handling, dust, etc or 
> tapes damaged by reason number two.
> 
> 4.) Your drives could be dirty.
> 
> Suggestions:
> 
> 1.) When you look at your save set messages, look for aborts 
> in the status and in the flag (ca,ta,etc). It only takes a 
> couple of problem clients to kill the overall backup job.
> 
> 2.) If your hardware supports make sure Tape Alert is 
> enabled. Networker will display the warnings in its logs.
> 
> 3.) Also block size relates to performance which in turn has 
> an effect on tape capacity. I configured my backup server's 
> OS to accept a larger block size than the 64K windows 
> default. The Legato Performance Tuning Guide has some good 
> information on testing and tuning.
> 
> 4.) Trying using just one or two drives. I backup 3.5TB daily 
> and I use
> 1 drive per backup server though each Server has two LTO-2 
> drives. Only on 1 Server do I use both drives. I try and 
> strike a balance leaning in favor of heavier multiplexing. 
> 
> Thanks,
> 
> Dana
> 
> -----Original Message-----
> From: Legato NetWorker discussion 
> [mailto:NETWORKER AT LISTSERV.TEMPLE DOT EDU]
> On Behalf Of rrevuru AT GMAIL DOT COM
> Sent: Friday, March 24, 2006 12:14 PM
> To: NETWORKER AT LISTSERV.TEMPLE DOT EDU
> Subject: Re: Networker Newbie
> 
> On 3/24/06, Greggs, Dana <c-dgreggs AT state.pa DOT us> wrote:
> >
> > When a tape is loaded into the drive, execute the following command 
> > ("mt -f" followed by your tape drive path) to see if hardware 
> > compression is
> > enabled:
> 
> 
> 
> 
> 
> Dana: This is what i see, for some reason i see there is 
> atleast 60GB worth of space is unaccounted for, and the 
> Volume=Full status. And if you guys take a look "Compression 
> Enabled" on my tape drives i believe.
> 
> 1. Is this problem troublsehootable?
> 2. Does it matter the data i am backing up, i am backing "File Server"
> 
> mt -f \\.\tape0 stat
> 
> 
> Media Capacity  = 204.90GByte
>  Media Remaining = 148.50GByte
>  Media Blocksize = 0
>  Media Partition Count = 0
>  Media is not write protected
>  default blocksize = 32768
>  maximum blocksize = 65536
>  minimum blocksize = 2
>  MaximumPartitionCount = 0
>  Partition = 0
>  Logical block position = 1
>  EOTWarningZoneSize = 0
>  Error Correction Enabled
>  CompressionEnabled
>  Features:
>   Performs SHORT erase operation
>   Performs LONG erase operation
>   Performs IMMEDIATE erase operation
>   Can report maximum tape capacity
>   Can report amount of tape remaining
>   Support FIXED block length mode
>   Support VARIABLE block length mode
>   Returns errors on write if tape is write - protected
>   Performs Hardware Error Correction
>   Supports hardware data compression
>   Can provide current absolute device block address
>   Can provide current logical block address and partition
>   Can physically load and / or unload tape
>   Support PREVENT / ALLOW Media Removal
>   Performs IMMEDIATE rewind operations
>   Allows Setting FIXED LENGTH or VARIABLE block sizes
>   Performs IMMEDIATE Load / Unload operations
>   Allows hardware data compression to be enabled / disabled
>   Can position tape to an absolute physical block
>   Performs IMMEDIATE absolute block positioning
>   Can position tape to a logical block(and partition)
>   Performs IMMEDIATE logical block positioning
>   Can position tape to END of RECORDED DATA
>   Can perform tape record positioning(backwards / forwards)
>   Can perform tape file positioning(backwards / forwards)
>   Can move backwards across records or filemarks or setmarks
>   Can write FILEMARKS
>   Performs IMMEDIATE tape mark write operations
> 
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