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Re: [K12OSN] Best Backup Solution for my situation...



Jim Wildman wrote:

crontab -e
will create a new (or edit the existing) root cron file which will be
independent of the cron.daily run.

The most efficient way to do disk to disk backups is probably with rsync
through a keyed ssh tunnel.

rsync -av -e ssh <source dir> <machine>:<dest dir>

once the keys are setup, then you won't need a password to run the
rsync.

On 26 Oct 2003, Terrell Prude', Jr. wrote:



The best practice for this is to get some sort of removable storage,
such as a tape drive, and take some of of that removable media offsite. 20GB (native capacity) DLT tape drives can be had on eBay for less than
$200 these days.


That said, the way I did "backups on a budget" was to do nightly copies
of directory trees over to other boxes whose job was solely to hold
backup data.  These other boxes would be in physically different parts
of the building, and I would do it at, say, midnight, so the users would
never notice the bandwidth usage.  You can put those 6GB disks in and
just start copying over subdirectories.  I would make a cron script to
do this.  On Red Hat Linux, you write your script (it's similar to
writing batch files), put it in the /etc/cron.daily directory, and edit
root's /etc/crontab.  The fields are as follows.  Some of this may look
familiar from using the Windows NT "at" command, since you mention that
you know Windows.

Minute - Minutes after the hour (0-59).
Hour - 24-hour format (0-23).
Day - Day of the month (1-31).
Month - Month of the year (1-12).
Weekday - Day of the week. (0-6; the 0 refers to Sunday).

Change the cron.daily time to whatever you want, and then let 'er rip. I usually stop and restart crond, just to make sure that my changes
take.


Note that the box holding the backup copy doesn't need a bunch of
oomph.  A 486 is actually quite sufficient for this.  Your "old pc" (AMD
150 or 300MHz) should have no trouble.

--TP


On Sun, 2003-10-26 at 01:04, Richard Ingalls wrote:


OK, thanks to the k12ltsp.org website and this mailing list I've put in two k12ltsp labs in my school, as well as a linux web/email server, squid/dansguardian proxy filter, firewalls, fileserver and a few standalone desktops. THANKS EVERYONE! Until the last two years, I knew nothing other than Windows...
I still feel very "weak" when it comes to my command line experience and real linux system administration skills. So, I need help.
How can I do backups? I don't have a tape system. BUT, I do have several 6Gb hard drives just sitting around. I also have many old PCs (AMD 150Mhz or 300 Mhz). Can I do backups over the network? How do I schedule the cron jobs to do this? OR, should I just install the extra hard drives in my existing linux boxes and do backups that way? (NO RAID on any of them).
What is the best practice for this situation?


*best* practices would have to include using RAID, at least software RAID 1, which can be had for the cost of a 2nd disk drive and some effort. Backups are very important, particularly with removable media like tape so you can have multiple generations, and recover things like deleted files. But disk failures are inevitable, and software RAID is cheap compared to system downtime while you acquire a new disk and perform a full system recovery, if all your eggs are in one hard disk.

Rsync is an alternative to both RAID and tape, but be aware that this means of backup does not preserve generations of files from any point in time other than when you last ran rsync (neither before nor after that time). And it does not prevent system down time to replace the disk and restore files if you do lose your hard drive. That said, rsync may be your best tool if what you want to do is keep a current copy of files on a separate system, possibly at a different location, for the purpose of fairly quickly switching which machine serves some function using those files in the event that you have a catastrophic failure of the first server, or a disaster.

So my recommendation is to use RAID, tape, and rsync, but for different purposes:
RAID for uptime in the event of hard drive failure (the most likely occurance)
tape for full system recovery or recovery of specific files/directories from some point in time
rsync for uptime in the event of catastrophic system failure (via manual or automated fail-over of services to the other system)





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