Topic: Suitability of Flexbackup...

[blakeh]

Just had an experience this last week that I'd like to share. Had a client who was doing backups to the Seagate Travan 20gb drive (10/20) all backup reports were good using flexbackup. Had to do a format and reinstall on the server due to a motherboard change, and made two additional tapes prior to reinstall.

Long story short:  All backups bad, even though flex reported them as good.  The restore would run and then just die, with an abort error in the log.  Ran flexbackup manually from command line and got same results.  Out of some 170k files, missing 17k.  After 3 straight days of all day all night efforts with tapes and research online, including reading comments from the author of flexbackup, we have learned the following:

As per the author of Flexbackup, when using it with Dump, as SME does, if there is a bad block on  the tape, doing a restore, flex is unable to read past that block and access any data on the tape after that.  Author recommends not using dump, but rather afio(?).  

We have sent the tapes to OnTrack with  the hopes they can recover the remaining client data.  I know that SME in the new version has changed to tar with flex, but don't know if that's going to make things any better.  Flex seems really underpowered to handle large volumes of data, and it doesn't seem to do any type of verify once it makes a backup, so as has been said in these forums before, your ability to do a restore isn't known until you try reading the tapes.

We're switching all our sme boxes to something else, either tapeware or Lonetar, any comments regarding experiences with either would be welcome.

Sorry if the above seems short on details and long on finger pointing, but staying up almost 4 days all day and all night working with these tapes and data has been exhausting...

bh

[Kelvin]

Hi Blake,

First of all, my sympathies about your backup woes. Been there.

This link :-
http://www.e-smith.org/bboard//read.php?f=3&i=32329&t=32329

has a discussion on the flexbackup / dump / tar thingy (admittedly, it does little to help your situation). I personally have moved away from flexbackup for any sort of production server using tape drives. I use Shad Lord's Arkeia contrib instead.

Past experience have also taught me to NEVER trust a Travan drive. I had a number of instances on Windows systems (whose software actually does a verify - something lacking in a number of Linux based backup software) where a backup to a Travan completes and verifies successfully but yet cannot be restored due to bad blocks etc. while restoring. Surprisingly, it verifies without a hitch - hence untrustworthy. Never had this problem with DATs, OnStream ADRs, DLTs or AITs, only with Travans.

I've just started to try Tapeware but have come across a stumbling block (nothing to do with Tapeware - probably something to do with SME). I cannot get Tapeware to recognise the Autoloader - just the drive itself. From reading up on this, it appears the kernel must be compiled with multiple LUN support (and I don't know if SME is or not) and we need to add an append line for max luns to lilo.conf. Must experiment some more. Hopefully, someone else may have come across this and know a definitive answer.

Kelvin

[dave]

As with Kelvin, I sympathize.  I used to work for a tape drive manufacturer many years ago (Tallgrass Technologies) and one of the keys I found to be a necessity is a verify alone won't always be enough.  I always recommended users do selective restores (to a different directory) and do a file compare of the restored files.

No medium will be 100% flawless 100% of the time.  Whatever backup device/software you end up moving to, I would highly recommend doing a selective file restore and compare immediately after the backup completes.  

I know none of this will help you now, just my 2cents worth.

[Boris]

bh,
give to tapeware a good try. It works great with all the tape drives and autoloaders. Restores are quick and easy. Disaster recovery option available.
We have had a while ago problem recognazing DLT loader with older version of TW. Tech support (even for evaluation) was able to send us updated config file and fix problem reasonable fast (in hours).
We also use it with DAT autoloaders and it works good, but you need to RTFM how to deal with scheduled jobs in this case.
It is not free unless you have single computer version comes with your drive, but cheaper then OnTrack recovery and saves your time and nerves.