Hello:
I know that a correct software mirror raid is subject to failures, when
anything wrong is written to both disks. And I also know that hardware
mirror raid is subject to hardware failures. I said at the beginning that I
keep two wheezy mirror-raid servers with the same data and software. Now
that mirror raid in all my machines is fully in order (also thanks to you)
I maintain three wheezy servers in the same situation (I recovered what had
been set aside in order to have three different jobs going on). That is
multiple backup. I can switch disks from one to another one.
Very large data files are at the supercomputer center, where multiple
backup is also carried out.
As to inexpensive ssh access to my machines and supercomputer center, I use
a cheap tablet, equipped with a physical US keyboard, where I installed a
minimal linux (ssh, text editor, browser). That allows continuous access
under a negligible electricity bill.
Thanks again for all your help
francesco
PS: You did not comment whether the pipe' command that I use to verify
grub has a general validity. As far as I could use it, I found it
equivalent to examining each disk, one at a time.
Cheers
francesco
On Sat, Oct 12, 2013 at 11:36 PM, Bob Proulx b...@proulx.com wrote:
Francesco Pietra wrote:
I hope not to bother beyond the limit, but the security of mirror raid is
something of utmost importance, at least in my work of biochemist, with
very limited ability in recovering from disk failures.
I must express concern. While RAID is very useful to keeping a system
running across disk failures that it is not a backup. Even with RAID
functioning perfectly it is possible to have accidental file deletion
and other file mangling. A known good backup is still required!
Having good RAID does not remove the need for a backup. Operating a
critical system without backup is a scary thing.
Important enough to repeat. A known good backup is still required!
Bob
