Disaster Planning for the Home Office, Part II

by Jonathan Gennick

I can't believe a week has gone by since my
first installment in this series
. You know, that's probably why I don't
have a disaster recovery strategy in place to begin with. When everything's
working fine, it's too easy to get caught up in the day-to-day grind and put
off planning for those inevitable problems that will occur at some undetermined
time in the future. If I had a hard drive crash actually scheduled, I'd be sure
to plan for the event, but no one schedules disasters.

Last week I identified the types of files on my systems. Today I want to go
into each of those files types in a bit more depth. I'll share my thoughts on
how important my different files are, and I'll think out loud about possible
backup approaches.

Following are my thoughts on protecting the different types of files on my

Digital photos: I'll suffer no economic loss from losing my photos,
only emotional pain. I'd prefer not to lose all my photos, but I can
certainly afford to lose some of them. I add new photos on an irregular
basis, usually not more than once per week, and often less frequently than that.

Master copies of my website files:
My live website serves as my backup. If I lose my master copies, I can just
download the files from my ISP and be whole again. Well, almost whole. I'd prefer
not to lose the originals of photos that I've cropped, optimized, or otherwise
doctored for my website. My website is relatively stable. I don't add content
nearly as often as I'd like.

Files for various books and magazine articles that I've written in the past:
If the book or article is already published, it's no great loss if I lose my
electronic copy. These files never get changed. Rarely do I even need to look
at them.

Files for books and articles that I'm currently writing: Now these are
really critical as they represent future income that I depend on. I don't want
to lose these at all, ever, under any circumstances. I don't even want to risk
losing a day's work, because if I have to rewrite something I may not be as
inspired as I was the first time. These files change frequently throughout the

Files for books that I'm editing for O'Reilly: The really critical files
here are those that I've edited, or am in the process of editing, which I've
not yet sent back to the authors. I don't want to lose any part of those files
for the same reason I don't want to lose any part of what I've written: it's
not fun to have to edit a chapter again because you lost the first copy. These
files, ones that I'm actively editing, also change frequently throughout the

Email files, archived emails, email address book: Losing my address
book would be a bit of a blow, because some important (to me) email addresses
only exist in my address book. Each time in the past that I've switched email
programs, and thus address books, I've managed to lose contact with a few acquaintances.
As for the email itself, it wouldn't be the end of the world if I lost it all.
Losing some of it would be preferable to losing all of it. Emails change very
frequently. However, I often go weeks at a time without adding to my address

Various personal files such as my resume, address labels, and so forth:
Files such as these can be recreated with a bit of effort. These files tend
to be very stable.

My Oracle database: Believe it or not, I actually have a licensed copy
of Personal Oracle8i. At the moment, I have no data in my database that I can't
easily recreate. That may change, but for now I'm not going to worry about this.
(Maybe I shouldn't duck this issue.)

Except for books and articles that I'm actively writing or editing, most of
my collection of important files changes, or gets added to, somewhat infrequently.
In addition, some loss in these areas is acceptable. A reasonable solution might
be to periodically archive these files to some sort of removable media such
as a CD-ROM. If I archived photos, websites, and other such files weekly, I'd
be willing to live with any loss that might result if a hardware failure or
some other disaster occurred during the week.

Files for books and articles that I'm actively editing or writing are another
matter altogether. No loss is acceptable. Well, that's my ideal. In the real
world, I may have to accept some risk. RAID is suggested here. In the event
of a hard-drive failure, RAID would protect me from losing data that had been
changed since my most recent backup. What RAID won't protect me from is a site
disaster such as a housefire. RAID isn't helpful when both mirrors are lost.
Frankly, I'm not sure what to do about the housefire scenario. I'll likely have
to accept some loss of data. I need to think on this some more.

It looks like my backup solution will involve some sort of removable media
such as CD-ROM along with IDE RAID. I'd prefer DVD to CD-ROM, but when I look
at the market for DVD writers all I see is confusion. DVD is preferable, because
a single DVD holds much more than a CD-ROM (no switching disks in and out),
but which DVD standard should I buy into?

So is this it? Is this my solution? Backup files periodically to removable
media and use RAID to protect myself from losing any changes that get made between
backups. Is that all I need to do? Certainly not. Tomorrow, after I drive down
to Dearborn for MacHack, I'll take a close
look at the various types of disasters identified in my previous
. After all, if a hard disk crashes, I not only need to have
a backup of the files, I need to have somewhere to restore that backup so I
can continue working. I need to think through the details of how I want to recover,
and how fast I want to be able to recover, from each of the scenarios I've identified.

Let me know what you think. Is CD-ROM a good media choice for periodic backups? What other choices do I have? And what about that housefire scenario?


2002-06-18 17:14:49
Network backups
One method I use is to do offsite incremental backups. Anything I do that I class as critical is in a CVS repository. When I dial up to my ISP during the day I rsync with a server I have elsewhere. (It also gives me a chance to regenerate web pages I've changed and tested locally.)

That way if the house burns down and I've lost my twin drives, I still have the CVS copy. All I will lose are any changes I've made since syncing. If one has ADSL one could easily have the repository automatically back itself up when files are committed.

CDs are good for permanent archival backups, but for offsite backups you do have to remember to take them off site (most people would probably do their backups before leaving the house unattended (by either sleep or leaving) and only one of those two situations results in 'off site').

Jonathan Gennick
2002-06-18 19:37:33
Network backups
Using CVS is a really interesting idea. It's especially timely too, as I'm currently editing a CVS book. Maybe I can put some of my newfound knowledge about CVS to good use, eh?