1. System Backup Strategies
MHVLUG Meeting
March 7th 2007
Michael “Porkchop” Kaegler
porkchop * porkchop * net

2. Backups: A definition...
The copying of data for the purpose of having a second copy of an original source in case of damage to the original data source.
Wikipedia
Important points:
There must be a full copy of your files on a different disk somewhere.
That copy must be maintained.

3. Backups: Storytime!
At an office in an unnamed educational institution...
All office PCs have access to the shared “N” drive, which is named “Backup”.
Student workers come in for the day, pick a random computer and copy their work from “N” to the local machine.
Students do their work.
At the end of the day, students copy their new work back to “N”, and delete the local copy.
“Why do I need to backup my backup drive?”

4. Meanwhile, two buildings away...

5. Dangers to innocent data
Source: Kroll Ontrack

6. But RAID does that!
“We have RAID on our servers so we don't have to deal with backups for our users.”
Redundant Array of Inexpensive Disks (or is it Redundant Array of Independent Disks?) (or is it Redundant Array of Inexpensive Drives?)
RAID-1 (“mirroring”)
Two disks, exact copies kept in sync automatically.
RAID-5
Three disks, 2/3rds data, 1/3rd parity.
Hardware failure?
Human error?
Software error?
Virus?
Natural Disaster?

7. Ok, I'll make a real backup! What to backup to...
How much data do you need to backup?
Just my financial data and crypto keys...
USB Jumpdrive CD
My , projects, sensitive data, crypto keys...
Tape
Remote drive
Get it all. I'll sort it out later.

8. So many choices... USB Jumpdrive
+ Physically small; can keep it with you.
-- Can get lost.
-- Dosn't hold much data.
CD/DVD
+ Cheap.
+ Portable.
-- Unknown archival time.
-- Low service life (often one-time-use)
-- Requires secure destruction.
-- Jukeboxes difficult to source and get working

9. ...so much data Tape + Portable. -- Expensive.
-- Slow, especially if you want to recover 1 file.
-- Requires secure destruction.
-- Drive must be replaced with similar on failure.
-- Not easy to get working, especially ATLs.
Remote Drive
+ Fast(er).
+ Always available.
-- Ends up on your power bill.

10. Costs
Price jump on CD and DVD due to addition of jukebox. (You're not going to feed a burner a disc every 10 minutes for 35 hours, don't kid yourself)
“Remote Disk” assumes you're buying John Forman's $200 p for the job, and paying for power.

11. Dangers to innocent data
Jumpdrive?
CD/DVD?
Tape?
Remote Disk?
Source: Kroll Ontrack

12. Key software... Homegrown rsync Automatable with ssh keys Open Source
tar c / | ssh 'cat>backups/blah.tar'
tar c / | nc backuphost nc -l -p > backups/blah.tar
rsync
Automatable with ssh keys
Open Source
336 Projects on Freshmeat
Amanda
BoxBackup
RIBS

13. Amanda The Advanced Maryland Automatic Network Disk Archiver
The old kid on the block – pretty popular in big installs.
Supports Windows
Supports disk, tape, optical, including jukeboxes.
Fairly complex initial setup.
Very powerful – if you have the time to learn it and the brainshare to keep it.

14. BoxBackup http://www.fluffy.co.uk/boxbackup/ Disk based only.
Can be run as an archival daemon...
Every time a file is changed, its sent to the backup server live.
Backissues of all files are kept.
Backup server can limit how many backissues are kept, how much space is used, etc.
Only changed files are uploaded to backup server.
Crypto everywhere!

15. RIBS Rsync Incremental Backup Script
Disk-based only.
rsync, ssh, cp, and php.
Uses hard links to make backup directories appear complete.
Doesn't always act like one would expect.
Backing up full systems gets slow.
Easiest to setup.

16. Tips KISS Fully automate your backups
You're never going to do them if you have to remember.
Human error
Test recovery procedures
You can summit Mount Everest, but if you don't make it back to the bottom alive, it doesn't count.
Do you have separate backups of the crypto keys you need to get to your backups?

17. More tips Know your filesystem Ext3fs is robust and reliable.
RiserFS has tail-packing.
Offsite backup if you're paranoid
Bring your tapes to work.
Google (and other online data stores)
Your most sensitive data becomes someone else's property. It never gets deleted.
Do you trust Google? Do you trust the company that will stage a hostile takeover of Google in ten years?

18. We're done! Now... Questions and Discussion Then...
The Palace Diner at 8pm
Later...
for lists, information about future meetings.
Next month...
We have a topic? You have a topic!