[OpenIndiana-discuss] Tape backup

[Doug Hughes]

On 3/17/2013 6:23 PM, Reginald Beardsley wrote:
> Tape as an archival medium has significant issues.  Reading poorly stored tapes is a "one try" proposition w/ no assurance of success.  The first high volume commercial application for digital tape was seismic data acquisition for the oil industry.  The oil companies had very detailed  cleaning and retensioning schedules w/ a large staff to perform them on the tape archives. Absent that level of care, reading old tapes is very difficult and requires great skill.  Old tape is NOT fun to work with.
>
> High capacity tape drives and tapes are not cheap either.  Blank LTO tape is almost as expensive as SATA disk. A ZFS based remote replicating server using triple parity RAIDZ is probably cheaper than tape.  For extremely large volumes and long archival periods, optical tape is probably the best choice.  But then you're probably working for the government.
>
> I would strongly urge comparing the cost of a ZFS backup server w/ daily snapshots to the cost of conventional tape backup. I think you'll be quite surprised at the implications.
>

reading old disks is a just as significant if not more of an issue, by 
my estimation. Try to find a machine that you can do low voltage 
differential disks with these days. That was only 15 years ago. what 
about SMD? The controllers keep changing over time. Also, after a disk 
has been in use for a significant period of time (say years), the 
lubrication on the platters tends to evaporate a little bit so that when 
you leave it off for a long period of time (days/weeks) it will stick to 
the heads and the platters. Tape doesn't have that issue.

An LTO5 tape is about $30 each, better in quantity. 1.5TB, more 
depending upon compression. That's an enterprise quality tape with much 
longer shelf life than a cheap deskstar disk if cared for properly. Even 
the cheap 1TB disks are $70. That's almost a 3X advantage. There's still 
a place for tape for archival, and yes, you do have to care for it 
properly, just like you have to care for everything else. But, cared for 
properly, tape should still outlive disk.

But, used it in its proper place. zfs snapshots make a lot of sense for 
online backups!