Jump to content
ShadeTek

Easily reduce tape backup/verify times in half.

Recommended Posts

Is it possible at some time in the future that Retrospect could talk to a tape drive manufacturer to make a drive that can verify the data that has just been put on tape as it does the backup.  This was available on Sony  Betacam video tape recorders 25 years ago and called confidence playback.  There was an extra set of playback heads just after the record heads that played back the just recorded data off the tape.  Could cut the time of a backup in half!

Share this post


Link to post
Share on other sites
1 hour ago, DavidHertzberg said:

Lennart_T is, as usual, correct (second paragraph of the section).

Thanks, you found what I was looking for, but didn't find.

A bit further down in that article:

"LTO uses an automatic verify-after-write technology to immediately check the data as it is being written,[42][43] but some backup systems explicitly perform a completely separate tape reading operation to verify the tape was written correctly. This separate verify operation doubles the number of end-to-end passes for each scheduled backup, and reduces the tape life by half."

  • Like 1

Share this post


Link to post
Share on other sites
44 minutes ago, ShadeTek said:

Thanks for the replies.  This would explain why Retrospect displays errors before it re-verifies.

ShadeTek,

When Retrospect does that, does it at least occasionally catch additional errors on the verify pass?  I ask because IM long-ago E a significant percentage of read errors for tapes were caused by something happening to a tape surface after it had been recorded on.

I should point out that my most recent ten years of tape experience was with DDS tape drives based on Digital Audio Tape technology.  Although Retrospect verify passes reported these as quite reliable—unlike previous tape drives I had used, the fact that DAT technology was fundamentally designed by Sony as a not-too-much-more-expensive replacement for the analog audio compact cassette meant it did not have any frills such as readback-after-write ÅFAIK.

I should also point out that my mainframe computer experience goes back to the mid-1960s, with 2400-foot half-inch-wide 7-track reel-to-reel tapes on drives that cost many tens-of-thousands of dollars.  You don't want to hear about that; it would spoil your digestion.:ph34r:

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×