A temporary suspension of operation, especially of electric
power.
When I woke up yesterday after a brief sleep I started to log back
in to different services and as I'm seeing something's funny with my
server, Jim over at #mobitopia
asks "is your site down?".
Damn.
As I checked what was happening, I could see that all sorts of
things were not working on the server. I was starting to fear the
worst ("the worst" in abstract, nothing specific) when I remembered
that I had seen similar symptoms a couple of months ago, and back then
it had been a disk space problem. I run "df" and sure enough, the
mountpoint where a bunch of data related to the services (including
logs) is stored was full (since November the number of pageviews a
month has increased to over 200,000, which creates pretty big
logfiles). As the last time, the logs were the culprits. Still
half-asleep, I start to compress, move things around and delete files,
when suddenly after a delete I stop cold: "No such file or
directory".
What? But I had just seen that file...
I look up the console history and four rm commands had
failed similarly.
Uh-oh.
I run "pwd". Look at the result. "That's not right...". I was
not where I thought I was.
At that point, I woke up completely. Nothing like adrenaline for
shaking off sleepiness.
I look through the command history. At some point in my switching
back and forth from one directory to another, I mistyped a "cd -"
command and it all went downhill from there. Adding to the confusion
was the fact that I used keep parallel structures of the same data on
different partitions, "just in case". I stopped doing that once I got
DSL back in May last year, opting instead to download stuff to my home
machine, but the old structure, with old data, remained. And, even
more, my bash configuration for root doesn't display the current
directory (the first thing I did after I realized that was add $PWD to
the prompt, but of course by then it was too late).
I had just wiped out the movable type DB, the MT binaries
(actually, all the CGI scripts), the archives, and a bunch of other
stuff in my home directory.
I took a deep breath and finished creating space, and moved on.
First thing I did was restart the services, now that disk space
wasn't longer an issue. Then I reinstalled the binaries that I had
just wiped out, which I always keep in a separate directory with some
quick instructions on how to install them. That turned out to be a
lifesaver, one of the many in this little story.
After that I put up a simple page that explaining the situation (he
re's a copy for... err... "historical reference"), plus a
hand-written feed and worked on the problem in breaks between work.
Then I realized that all the links that were coming in from the
outside (through other weblogs, google, etc) were getting a 404. So as
a temporary measure I redirected the archive traffic to the main page
through a mod_rewrite clause:
RewriteRule
/d2r/archives/(.*) /d2r/ [R=307]
That would return a temporary
redirect (code 307) while I got things fixed (one fire out! 10 to
go).
So what next? The data of course. When I came back to Ireland at
the beginning of January I started doing backups of different things
(a "new year, new backups" sort of thing), and I backed up all the
server data directories on Thursday, and then on Saturday I did what I
thought was a backup of my weblog data, through MovableType's "Export"
feature. As things turned out, the latter proved useless, and it was
the "binary" backup that saved the day.
Why? Well, as I started looking at things, I went to MT's "import"
command in cavalier fashion and was about to start when the word
"permalink" popped up in my head. Then it grew to a question: "What
about the permalinks?".
The question was valid because my permalinks are directly based on
the MT entry ids. Therefore, if an import changed the entry IDs, it
would also break all the permalinks. I started cursing for not
switching over to using entry-based strings for permalinks, but that
didn't help. So I did a little digging and I realized that I was
right. MT assigns entry IDs on a system-wide basis. So if you have
multiple weblogs on the same DB (which I have, some of them private,
some for testing, etc) OR if you have to recover the data from an
export (which I had to do) you're out of luck. More likely than not,
the permalinks will not work anymore. The exported file did not
include IDs. Re-importing would generate the IDs again. Different IDs.
Different links. Result: broken links all over the place, both within
the weblog and from external sources.
This is clearly an issue with the MT database design, which doesn't
seem too well adapted to the idea of recovery. To be fair, however, I
am not sure how other blogging software deals with this problem, if at
all. I think this is one big hole in the weblog infrastructure that we
haven't yet completely figured out, both for recovery and for
transitions between blog software (As Don noted recently).
This is when I started thinking that things would have been much
easier if I had written my own weblog software. :) That thought would
return a few times over the next 24 hours, but luckily I was busy
enough with other things not to indulge in it too much.
After looking online and finding nothing on the topic, I came to
the conclusion that my only chance was to do a direct restore of the
"binary" copy (that is, replacing the clean database with the backup
directly) I had from last Thursday. I did the upload, put everything
in place, and things seemed to go well, I could log in to MT and the
entries up to that point where right where they had to be. So far so
good. I was going to do a rebuild and I thought that maybe now was a
good time to close off all comment threads in all entries (to avoid
ever-increasing comment spam) and I spent some time trying to figure
out how to use the various
MT tools to close comments on old entries. However, they all seem to be ready
for MySQL rather than BerkeleyDB. It wasn't a hard decision to set it
aside and move on.
So I started a full rebuild. The first 40 entries went along fine,
albeit slowly. Then nothing happened. Then, failure. I thought for a
moment that, for some strange reason, the redirect I had set up
yesterday was causing the problem, so I removed it, restarted the
server, and Tried again. Failed again. No apparent reason.
I got angry for a second but then I remembered that the "binary"
backup was of everything, including the published HTML files.
Aha! I uploaded those,crossed my fingers, and did a rebuild only of
the index files, and everything was up again. Actually, this was
important for another reason, since the uploaded images that are
linked from the entries end up by default in the archives
directory, you need a backup of that or the images (and whatever else
you upload into MT) will be gone if you lose the site.
So the solution up until this point had been a lot simpler than I
thought at the beginning.
But wait! All the entries after last Thursday were missing, and I
didn't have a backup for those. That was when RSS came to the rescue
in three different forms: 1) I download my own feeds into my
aggregator, so there I had a copy up to a point. 2) Some kind souls,
along with their condolences for the problem, sent along their own
copy of the latest entries (Thanks!!--and Thanks to those who sent
good wishes as well). 3) Search engines, (Feedster was the most up to
date--btw, it was Matt that
suggested yesterday, also on #mobitopia, that I check out Feedster as
a source of information, a great idea that really applies to many
search engines if their database is properly updated), had cached
copies that I could use to check dates and content. So armed with all
that information I set out to recreate the missing entries.
Here the problem of the permalinks surfaced again. I had to be
careful on the sequencing, or the IDs wouldn't match. So I re-created
empty entries, one-by-one, to maintain the sequencing (leaving them
unpublished), actually posted a couple of updates<
/a> of what was going on, and then I published the recovered entries
as I entered the content and set the right dates.
So. All things are restored now (except for the comments from the
last week, which are truly lost--this makes me think that setting up
comment feeds would be a good idea. However, that doesn't address how
would I recreate the comments given what happened. Would I post them
myself under the submitter's name? That doesn't seem right at all.
Another problem with no obvious solution given the combination of
export/ID issues with MT).
What's strange is that there's been slight a breakdown in
continuity now, because I did "post" some updates to that temporary
index file, but it couldn't be part of the regular blogflow. Hopefully
this entry fixes that to the extent possible.
Okay, lessons learned?
- Backups do work. :) I am going to do
another full backup today, and I'll try to set up something automated
to that effect. (Yes, I know I should have done it before, but as
usual there are no simple solutions, and then you leave it for the
next day... and the next...). Plus, backups for MT installations,
should always be both of the DB and the published data, to make
recovery quick. (I have about 1500 entries, which amount to something
like 20MB of generated HTML--additionally, the images are posted
directly on the archives directory, so if you're not backing that up,
you've lost them).
- For MovableType, the export feature is not so great as far as
backups are concerned. The single-ID-per-database problem is a big one
IMO, and I don't think MT is alone in this. We need to start looking
at recovery and transition in a big way if weblogs are going to hit
the mainstream (and we want permalinks to be really permanent)
- Solutions are often simpler than you think, if you have the right
data. Having a full backup makes recovery in this case easy and fast.
- This stuff is still too hard. What would a less
technically-oriented user do in this situation? Granted, it was my
knowledge (since I was fixing stuff directly on the server) that
actually created the problem in the first place, but there are
lots of ways in which the same result could have been "achieved",
starting from simple admin screwups, hardware failures, etc.
Overall, this has been a wake-up call in more than one sense, and
it has set off a number of ideas and questions in my head. How to
solve these problems? I'll have to think about it more.
Anyway. Back to work now, one less thing on my mind.
Where was I?
Grok Description matches for Squirrel Blamed for Outage, Traffic Jam (AP)
GrokA matches for Squirrel Blamed for Outage, Traffic Jam (AP)
Squirrel Blamed for Outage, Traffic Jam (AP)
