[SATLUG] backup recommendations

[Daniel J. Givens]

I'm not saying tape backup is old and dying. Tape is good when you need to keep
long term archives or you do not have the bandwidth/infrastructure to do remote
backups, but still want some backups stored off site. As a whole though, I do
not trust tapes as much as I trust redundant disks. Do I trust individual disks?
Hardly.

There have been several times at work that I've had to turn off all of our
servers over the weekend while crews worked on the HVAC system. Come Monday
morning, every single time, I lost one or two drives, but I have every server
come up thanks to our servers being setup on RAID 5 arrays with a hot spare.
Thanks to the hotswap capabilities of my servers, I was able to swap the drives
and let the RAID rebuild itself while the system was online. Typical setup.

My backup needs, both at work and at home, do not call for long term archiving.
I understand that in some businesses, you have to maintain backups for legal
reasons. I think tape is great for that, especially when you start to consider
the electricity costs of the additional spinning drives required and the fact
that larger storage costs exponentially more the higher you go. But if you don't
need to maintain those long term backups, the advantages of tape start to wane.

This probably goes without saying, but when you start to look at backup
solutions, you have to look at the needs you must meet. If you write to a tape
once and throw it in an off-site archive and NEED to keep those backups for
months or years, then I think you've found the solution that works for you. If
write to a tape and then write back over it again within a month, you can
probably stand to ditch the tapes and go with a disk to disk solution. It all
depends on your data retention needs.




Al Castanoli wrote:
> You have a lot more faith in disk drives than I do.  I do back up to
> disk, but after restoring an entire datacenter from tape after Hurricane
> Andrew over ten years ago, I still back up to tape.  For examble: I'm
> currently backing up around 50GB per night on just one of my servers to
> tape, and intend to continue doing so, even though the machine I'm
> backing up has a failover server that updates every five minutes.  I've
> had occasion to recover data off those tapes four or five times a month
> to show what was on the server at an earlier date.  I'm using a tape
> changer and don't have to worry about overwriting older data when the
> robot has removed a tape from the tape drive.  To get the same
> functionality from disks, I'd have to invest in several more terabytes
> of space for disk drives that rarely approach their MTBF ratings these
> days.
> 
> Long story short - backing up to remote disk drives is fast, fairly
> reliable, and much easier than backing up to tape if you're writing your
> own backup scripts rather than using some pointy clicky gui thingy for
> backups, but that doesn't mean backing up to disk is the right solution
> in all cases.
> 
> For the Linux servers I have running near the Pacific coast, I use mtx,
> mt, dump, and restore from the command line to do manual tape backups,
> and script those commands into my cron driven backups.  Except for the
> terminal I ssh into those servers with, the servers are firewalled off
> from contacting other machines, and the customer will not allow
> exceptions. so offsite rdist syncing or some other hard drive backup
> routine is not possible.