Unix

Yes, I hate google too. They do way too much to make my life harder. On the surface they are all nice and soft, but their 'free' services have a ton of bad sides to them. Let's take a look at one right now. Today I found a nasty shortcoming of gmail. All google apps users will have the same shortcoming.

So, Google has a bunch of mailservers that accept->deliver mail for gmail users. When you are want to send an email from your email client, you need to configure it to use TLS and authentication. That's great in terms of security for regular users. But what if you run a mailserver and want to send mail to some gmail user and TLS encrypt it? Turns out it is not possible. You, in fact, have to configure your mail server as if it is an email client, that is authenticate and then TLS encrypt, What's even worse is that even if your mailserver supports TLS encryption, gmail will plainly ignore it, so all mail users send out of gmail mailservers is transferred unencrypted.

here are snippets of configuration for postfix and exim to make it work, but in reality, you should really dump this google service and start using something more reliable and feature-rich.

exim(must be compiled with tls and sasl):
in routers create a new router. it will only be used when sending email to gmail users. if you are google apps user, add your target domains here.

gmailrouter:

  driver = manualroute

  domains = gmail.com

  route_list = gmail.com smtp.gmail.com

  transport = gmailtransport

in transports:

gmailtransport:

  driver = smtp

  hosts_try_auth = ${if exists{CONFDIR/passwd.client} { ${lookup{$host}nwildlsearch{CONFDIR/passwd.client}{$host_address}} } {} }

create a file called passwd.client which should contain smth like that:

smtp.gmail.com:username@gmail.com:your_pwd

postfix:
in main.cf file add:

relayhost = smtp.gmail.com

smtp_sasl_auth_enable = yes

smtp_sasl_password_maps = hash:/etc/postfix/relay_pwd

smtp_sasl_security_options =

in your /etc/postfix/relay_pwd you should have something like that:

smtp.gmail.com  username@gmail.com:your_pwd

don't forget to run:

 postmap hash:/etc/postfix/relay_pwd

This is for all of you, unfortunate sysadmins, who support companies who made a decision to use gmail or google apps. good luck.

a few months ago I wrote about php version 5.2.8 being very low quality. 5.2.9 was out a few days ago and I decided to give it a try hoping all issues are resolved. it looks like it became even worse. after running for 5 minutes relatively OK, although with higher loadaverage, php started performing so badly, that it caused apache to spawn as many children as it was allowed, which resulted in system going 375MB into swap. it sure seems like the higher the version of php gets, the worse it is performing. of course these graphs will give a much better idea:



I let it run for about 20-25 minutes to get good graphs. couldn't let it run any longer because I started getting alerts about abnormal load.

the only difference was the version. php 5.2.9 was compiled exactly the same as the stable 5.2.6. same modules, same hardware, same code to run.

you suck, php. :(

saw a great example of how crappy VM management is implemented in linux. had a mysql server as an idle slave of the main mysql database running for days. was making backups of it, so it had all the data in RAM. switched to it from another slave and suddenly it started crapping out.
take a look at this top snapshot:

---

top - 21:33:00 up 32 days, 10:56,  1 user,  load average: 27.02, 17.08, 7.93

Tasks: 104 total,   4 running,  99 sleeping,   1 stopped,   0 zombie

Cpu(s):  6.9%us, 92.9%sy,  0.0%ni,  0.0%id,  0.1%wa,  0.0%hi,  0.1%si,  0.0%st

Mem:  32941100k total, 32785596k used,   155504k free,     1164k buffers

Swap:  2096472k total,      812k used,  2095660k free,    74972k cached

 

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND

 1834 mysql     15   0 34.1g  31g 5084 S  580 98.9 920:17.30 mysqld

  870 root      11  -5     0    0    0 R   72  0.0  11:56.62 kjournald

  565 root      20  -5     0    0    0 R   68  0.0  17:00.23 kswapd0

  696 root      15   0     0    0    0 S    1  0.0   0:37.72 pdflush

    1 root      15   0 10324  464  352 S    0  0.0   0:56.23 init

---

all the RAM is used by mysql, there is no swap being used, yet kswapd0 is effectively wasting as much as it possibly can. what is it doing? who knows, all I know is that there is no disk i/o. what can a kernel swap process do when there is no swap used and there is no disk i/o? kjournald is wasting some resources too. why? who knows. what a brainless VM management. :(