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Daemonic Dispatches
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Musings from Colin Percival
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Upcoming posts
I've had a lousy summer. First I got bronchitis; then as I was recovering
from that, my wrists started hurting. Since I know several people who
ended up effectively unable to work due to wrist pain, I took this as a
sign that I should cut down on the amount of typing I did -- and posting
here was one of the first things I cut. An ergonomic keyboard, two wrist
braces, and many weeks later, I think my wrists are improving
(but they might get worse again -- I thought they were improving last
week, and the week before last, too), so I wanted to give a quick preview
of some of the things I expect to be writing about in the next few
weeks... wrists permitting, of course.
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High performance single-threaded access to SimpleDB
Last month, Amazon published a
code
sample which demonstrated the use of SimpleDB as a repository for
S3 object metadata. This code sample would probably have gone almost
completely unnoticed if it were not for one detail: Using a pool of 34
threads in Java, the code sample sustained 300 SimpleDB operations per
second when running on a small EC2 instance. Only 300? We can do
better than that...
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Dissecting SimpleDB BoxUsage
Billing for usage of a database server which is shared between many
customers is hard. You can't just measure the size of databases, since
a heavily used 1 GB database is far more resource-intensive than a
lightly used 100 GB database; you can't just count queries, since some
queries require far more CPU time -- or disk accesses -- than others;
and you can't even time how long queries take, since modern databases
can handle several queries in parallel, overlapping one query's CPU
time with another query's disk time. When Amazon launched their
SimpleDB service, it looked like they had found a solution in BoxUsage:
As the website states,
Amazon SimpleDB measures the machine utilization of each request and
charges based on the amount of machine capacity used to complete the
particular request [...]
and reports back a BoxUsage value in every response returned by
SimpleDB. Sadly, this "measurement" is fictitious: With the possible
exception of Query requests, BoxUsage values returned by SimpleDB are
entirely synthetic.
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Amazon S3 data corruption
Amazon S3 recently experienced
data
corruption due to a failing load balancer. While the tarsnap
server currently uses S3 for back-end storage, tarsnap was not affected
by this.
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To everything a season
On April 11, 2003,
FreeBSD Update
was committed to the FreeBSD ports tree. This binary security update
system, which started out by supporting FreeBSD 4.7-RELEASE and added
support for newer releases as they came out, was the topic of
a paper
I presented at BSDCan'03 and is probably the leading factor behind
my becoming a FreeBSD committer and ultimately the FreeBSD Security
Officer. For five years, I distributed updates via
update.daemonology.net; but that site has now outlived its
purpose, and I have now taken it offline.
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Daemonic Dispatches: Now with comments
I've resisted allowing people to post comments here for a long time: I always
figured that readers could always email me if they wanted; and in any case,
allowing users to post comments would have meant writing more code, running
CGI scripts (the entire blog is static files, recompiled whenever I want to
add or change something), and generally fell into the category of "more work
than it's worth". It looks like Disqus
might have changed that.
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Even faster UTF-8 character counting
I recently came across two articles,
"Counting
characters in UTF-8 strings is fast" by Kragen Sitaker, and
"Counting
characters in UTF-8 strings is fast(er)" by George Pollard, which
provide a series of successively faster ways of (as the article names
suggest) counting the number of UTF-8 characters in a NUL-terminated
string. We can do better.
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Tarsnap beta testers wanted
As of today, everybody who has contacted me to express an interest in
beta testing tarsnap, my upcoming
online backup service, has been invited to start beta testing.
A few bugs have been uncovered by beta testers, but I've fixed all of
those; so tarsnap currently has no known bugs. What does "no known
bugs" mean? It means that I need more beta testers!
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The upgraded freebsd-update server
I wrote recently about the
surge in traffic
to update1.freebsd.org after FreeBSD 7.0 was released. I
was concerned about whether the server could continue to handle the
load in the future -- until I received an email from
Layered Technologies.
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Security is Mathematics
In a recent editorial in Wired News, Bruce Schneier commented on the
twisted
mind of security professionals; that is, the way that we look at
the world, always questioning hidden assumptions -- like the assumption
that someone who buys an ant farm will mail in the included card asking
to have a tube of ants delivered to his own address, rather than
someone else's address. Schneier suggests that this "particular way of
looking at the world" is very difficult to train -- far more difficult
than the domain expertise relevant to security. I respectfully differ:
In my opinion, this mindset is not particular to security professionals;
and universities have been successfully training people to hold this
mindset for centuries.
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FUG-BR - Espalhando BSD |
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Dicas Rápidas: |
O portsclean(1) é uma ferramenta que limpa todo o diretório work/ do ports(7). Além de liberar espaço em disco ele é capaz de remover arquivos antigos que não possuem referência no /usr/ports/distfiles.
#portsclean -C
Limpa o diretorio work/
#portsclean -D
Limpa o diretorio distfiles/
#portsclean -i
Modo interativo, pergunta se você quer remover o arquivo
Recomendado
#portsclean -CDi
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