Hello Bob I agree with b and c, but there a can be a little misleading as we learned the hard way this past year. Netbackup records the start of a fragment and not the location of the file on the tape. So it has to read the whole fragment until it finds the file it is looking for.
len -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of bob944 Sent: Wednesday, April 30, 2008 9:03 PM To: veritas-bu@mailman.eng.auburn.edu Subject: Re: [Veritas-bu] Multiplexing on VTL's > My main concern is that when doing restores off a multiplexed > tape, the VTL READ speed off the disk(let's say it's 80MB/s) > is the same whether there's MPX in the stream or not. The > restore will throw away the bytes that doesn't belong to the > client, so out of a 80 MB/s stream coming off the disk, you > will throw away (let's say) 60MB and use only 20. It's this > reduction in effective restore speed that's my main concern. Perhaps you'll have time to test and share here? I'd expect NetBackup to treat it as multiplexed tape and not read the intervening data. IME, most multiplexed-tape-restore horror stories are no longer valid due to a) fast-locate-block's ability to skip the intervening data (I have never explicitly tested this), b) drives that supply data faster than the client can write it and c) properly designed multiplexed backups can restore multiple clients significantly faster than non-muxed (I have tested b and c). _______________________________________________ Veritas-bu maillist - Veritas-bu@mailman.eng.auburn.edu http://mailman.eng.auburn.edu/mailman/listinfo/veritas-bu