More on Disaster Planning for the Home Office

by Jonathan Gennick

In my last blog
entry on this topic
, I thought through the different types of files that
I have on my system and the correspondingly different levels of protection they
each need. Now I want to think about the different types of problems I might
experience and how I might recover from each. First however, just three days
ago, on 21 June, I received the following email from an author:



I have experienced a system crash on my computer --- thus, I don't know how
much writing I will be doing over the next weekend and (possibly week) as
I
recover my system. I don't think I have lost any data regarding [book title
omitted], but I need to rebuild my system ASAP.



Wow! What a timely reminder of how vulnerable I am. This is exactly what I
don't ever want to have happen to me. Notice the author believes he may be out
of commission for up to a week. A week! That's much too long for me to be unable
to work. I personally want to be able to resume working in a matter of an hour
or so should anything go awry with any of my equipment. And he only "thinks"
he hasn't lost any data pertaining to the book he's currently writing. I want
to "know" that I haven't lost anything, at least anything important.
With this mind, I want to think through the various disaster scenarios that
I might experience.


Bear in mind while reading these scenarios that I use two computers in my day-to-day
work: one running Windows XP and one running Suse Linux 8.0. The Windows XP
box is where most work happens, and it's the most critical. My Linux box exists
only to run Oracle. I can usually tolerate more downtime on the Linux box than
on the XP box.


I might accidentally delete an important file — I can't remember
the last time this has been an issue for me. Book and article files get traded
around by email so much that if I do delete one by mistake, I can almost always
count on having a copy in my email archive. And there's always the Recycle Bin.
I'm not going to take any specific action to protect myself from this scenario.


My hard-drive could fail — If my XP hard-drive fails, I want to
be able to plug another hard-drive in, restore the files, and go. If I buy into
RAID, which I'll almost certainly do in order to prevent the loss of even an
hour's hard writing work, recovery from the loss of a hard-drive will be trivial.
I should probably keep a spare hard-drive on hand though, because even with
RAID I'll be exposed until I replace the drive that failed.


My Linux box has two drives. I can mirror all the critical Oracle files: control
files, redo logs, and archive logs across those two drives. So long as I periodically
backup my database, I'll be able to recover it in the event of a drive failure.
But such a recovery probably won't be a one-hour affair. I'll have to install
a new drive, possibly reinstall Linux, and only then deal with recovering Oracle.
The spare drive I keep on hand for my XP box can come in handy for this scenario
as well. I could use Suse's software RAID on my Linux box. Maybe someday I will.
For now though, I'm going to use the two drives as separate disks in order to
give me more disk space to play around with. I have a spare Oracle instance
on my XP box that I can use in the event the Linux box is down, so recovering
quickly from the failure of a hard-drive on my Linux box is not a priority.


Some notes here: I have absolutely no clue how to replace just one hard-drive
on my Linux box with a new one. How would I partition the new drive so that
it matched the drive I was replacing? How would I do the low-level format? The
only way I know of to do these things is to reinstall Linux. I should probably
practice this scenario. Another issue: some article topics that I choose do,
in fact, make me very dependent on my Linux box, albeit only for a short period
of time. When I wrote about enterprise
users
for Oracle Magazine, I ran the database on Linux and my LDAP directory
server on XP. While writing that article I needed both boxes to continue functioning.


Some other component could fail, leaving the hard drive intact but the computer
unusable
— If my XP box goes down and the hard-drive is left intact,
my plan is to take the hard-drive out, move it to my Linux box, and make that
my new XP box. In essence, my Linux box serves as a spare computer. Both boxes
are the same model of Dell Dimension; the only difference being the NIC and
video cards. XP should auto-detect those cards as new hardware, reconfigure
itself, and I should be in business. Hmmm... I wonder whether XP's product activation
feature would give me grief in this scenario. I'll try and find time to do a
test-run this week.


In the event that my XP box fails and I also need my Linux box up and running,
I do have a company-issued notebook computer that sits on the shelf when I'm
not travelling, and that I can press into service as a spare. The notebook runs
Windows 2000, and has a version of Microsoft Office on it, and also a copy of
my email program. Other apps that I use are not on the notebook, but are less
critical to my day-to-day work (I hope). The problem would be in getting my
current work files off the hard-drive from the XP box that failed and onto the
notebook's hard-drive. At CompUSA last week I saw an external hard-drive enclosure
that provided a USB 2.0 (or was it Firewire) interface. If I put my desktop
hard-drive into such an enclosure, I could access that drive from my USB-enabled
notebook. Maybe. I've had mixed-luck with USB under Windows 2000. My USB scanner
works; my USB camera doesn't.


If my Linux box goes down leaving its hard-drives intact, I'll just order new
parts via overnight deliverey and let it stay down until I can be bothered to
install the new parts.


A peripheral, such as a monitor or a printer, could fail — I have
spare monitors and two printers. Nothing to worry about here that I can think
of.


A housefire, theft, or some other major event could cause me to lose all
my computers, their hard-drives, and any backup media I might have

This is a scenario I hope I never need to deal with. My current thinking is
that I'll make archival copies of completed book and article projects and store
them in my mother's apartment, which is only four blocks away. I'll do the same
for my photos and web sites; I can tolerate some loss of photo and web site
files in the event of a major disaster such as a fire. Writing files for current
projects are another matter. I'm thinking I can write some sort of script to
copy those to my ISP on a daily basis.


I could get hit by the proverbial truck — This is different. Rather
than lose data, I lose me! This is my least favorite scenario <grin>.
The issue here is that various people depend on my knowledge of my systems:
my wife depends on me to know where our budgeting and money files are, my family
depends on me to know where the photo files are kept, my authors have sent me
their chapters, and my company wishes to ultimately get those chapters. It would
be a nice gesture on my part were I to leave some written documentation of how
I organize book files and such so that in the event of my demise the people
who need to get at those files can.


*   *   *


I don't think I've covered every base yet with respect to the above scenarios.
There are obviously some things I haven't figured out, and lack of money will
prevent me from covering every possible scenario to the degree that I might
like. For example, I can't afford, or at least don't want to afford, RAID on
both my XP and Linux boxes. And if an expensive component gives out on my Linux
box, I probably won't want to part with the cash to order a new part right away.


Much of my work is deadline-driven. One of my goals in the event a recovery
scenario occurs, is to be able to get on with work quickly. It's ok if the ultimate
resulotion is a week or more in coming, so long as I can quickly and easily
find some other way to get work done in the meantime. For example, if my Linux
box goes down I usually will be able to get by for some time using the spare
database on my XP box.


This is the last of my "thinking it through" blog entries. I'm beginning
the actual implementation of a recovery plan. I took advantage of my recent
trip to Detroit for MacHack to pick up a CD writer. I'll install that soon and
use it to make those offsite copies, and to backup files that don't change often
(photos, old book projects, web sites). And then I need to find even more money
for a RAID card and spare drive for my XP box. I'll probably test the scenario
of my XP box failing sometime in the next week or two, so that I can see what
happens when I install the intact hard-drive into the box that is now running
Linux. I also need to find some software, or write some scripts, to help me
backup files on a regular basis. I need to automate as much of this work as
I can. The more I have to consciously think about making backups, the less likely
they are to get done.



Have I thought through these scenarios well-enough? Let me know. You can leave a talk-back message in this article, or you can email me at jgennick@oreilly.com.