What?
Control Groups aka cgroups – see the docs .
Resource control and monitoring.
Some examples follow for throttling i/o speed(s) for a process control group (cgroup).
Continue reading “adventures with cgroups for resource control”
Dell t300 – Buying an ancient server
So, one of my office servers was misbehaving – and random crashes finally tipped me over the edge.
Read on a blurb of text about buying an ancient computer from ebay and some uninteresting pitfalls encountered.
Bash random number generation
Historically I’ve used $RANDOM as a random number source in bash — a bit like :
RAND=$(( $RANDOM % 10 ))
when I’ve needed a random number out of 0,1,2,3,4,5,6,7,8 and 9
one problem with this is that $RANDOM itself is populated between 0 and 32767 by the shell – so it’s not going to give totally even distribution.
Finally, I discovered ‘shuf’ — usage like :
shuf -i 1-100 -n 1
-i RangeFrom-RangeTo
-n how many
So –
RAND=$(( shuf -i 1-10 -n 1))
ack-grep config – ackrc – adding new file types
I needed to add some more file types for ack-grep to find / search when I’m looking for PHP code that resides in files with non-standard extensions (e.g. something.def, something.inc etc).
Continue reading “ack-grep config – ackrc – adding new file types”
MySQL Max_connections stuck on 214 ?
I found MySQL was being annoying earlier and not ‘accepting’ my max_connections = 450 directive on a Debian Wheezy install, and being seemingly stuck on having 214 connections….
More monitors.
I have an Intel NUC d54250wyk as my work computer (it’s a little dinky thing, which somehow manages to pack a reasonable punch).
On board it has a mini-hdmi port, and a mini-display port – which I used for a dual monitor configuration.
But two monitors is so last year …. and after 5+ years of having two monitors to stare at, I thought it was perhaps time to move up to 3 (or more).
Continue reading “More monitors.”
BTRFS gotchas… (balance / scrub / snapshots / quota)
I’ve been using BTRFS for a few weeks now, and some bits are great (filesystem snapshots, dynamic resizing etc).
The “Good” and “Bad” things follow:
Continue reading “BTRFS gotchas… (balance / scrub / snapshots / quota)”
Squid 3.4.x for with transparent ssl proxying/support for Debian Wheezy.
I needed a variant of Squid which supported transparent SSL interception (i.e via iptables redirection) so I could log outgoing HTTPS requests without the client being aware.
The stock wheezy variant doesn’t support SSL (see : Debian Bug Report).
Even after recompiling Wheezy’s squid3 it didn’t seem to work (perhaps my stupidity) so I ended up moving to the latest-and-greatest squid (3.4.9 at the time of writing) and getting that to work. Brief notes follow.
Continue reading “Squid 3.4.x for with transparent ssl proxying/support for Debian Wheezy.”
Postfix – connect from unknown[ip.address]
One server I poke around on, has a number of postfix instances
(see: postmulti).
Interestingly, one instance was logging things like :
Oct 26 22:02:05 mail postfix-blah/smtpd[59158]: connect from unknown[1.2.3.4] Oct 26 22:02:05 mail postfix-blah/smtpd[59158]: CA9292EE2C0: client=unknown[1.2.3.4]
Continue reading “Postfix – connect from unknown[ip.address]”
Ansible – some random useful things.
Some random useful things for Ansible users: