C7975A LTO5 tape lifespan after several full back-ups

[Krishius]

Hi there!

I am trying to find out how much each full back-up to LTO5 tape shortens the tape lifespan.

For starters, a short description of my system and its purpose:

I have a HP Ultrium 3000 SAS external tape drive connected to ProLiant server with RAID running CentoOS 6.5 and LTFS v2.1.1. I am doing manual back-ups and archives of video files to LTO5 tape (using LTFS, as mentioned before) as an alternative for archiving data to hard disk. Main purpose is long term archive of the data.

Majority of tape media is HP C7975A rewritable LTO5 tape. I usually fill the tapes full or close to full in one pass, i.e.. I collect enough data to fill one tape and copy it one non-stop pass using CentOS standard file manager (drag & drop from RAID folder to tape). Often some of those video files are re-done/revised/updated/some errors corrected, and I have to update those archives as well, that means I have to re-write the whole tape, which means that I am formatting the same tape anew and filling it again the same way it was written before with updated data.

Some tapes are fully re-written for about 5 to 7 times (each fill is one full copy pass, as mentioned before).

Let's assume that after 7th re-write pass there is no more updates/re-writes necessary and tape is put on the shelf for long term archive.

What is expected shelf life for such tape, that has been re-written for 7 times? How much each full re-write pass shortens tape shelf life?

I have read in several sources that LTO5 media is capable of 260 full back-ups. However, it is not mentioned anywhere (at least I cannot find any information), can the tape still be used for long-term archiving after so many cycles. I also believe that this parameter is more linked to automated tape libraries and the way those libraries handle tape media, and not for small single-drive manual systems.

Thank you in advance,

Kriss

P.S. This thread has been moved from Tape Backup (Small and Medium Business) to Tape Libraries and Drives. -HP Forum Moderator

[Curtis Ballard]

The primary contributor to the media life is the ability to get the data onto the media.  Not so much getting the data off of the media.

LTO drives perform read after write and test the quality of the data that was written.  If the data wasn't written sufficiently for long term storage, then the drive will write the data again and loop until it is satisfied that the data is well written.  There may be some change in the long term storage life when a well used tape is written but I haven't seen any test data.  The life probably wouldn't be significantly different because anywhere that the data isn't written perfectly there is going to be several copies of the data which can be used to recover the original data.

I've looked at a number of test results for writing the tape repeatedly and the writes start out really good but improve a bit over the first few writes and then settle out for quite a few full volume writes before any degradation is seen.  I think that tapes written 8-10 times should be writing at about the peak quality and should be ideal for long term storage.

[Krishius]

Curtis,

Thanks for your reply!

But what is expected shelf life for LTO5 tape in long term, if tape is written once or re-written several times in the very beginning (withing few months) and then stored untouched for years?

Kriss