You are here: Home / Archives for Linux

A testimony to Linux resilience

by

A client released a new version of their website onto 20 AWS m1.medium instances (current site at peak load runs approximately 60 m1.medium webservers).
It was clearly an unsuccessful release, but what was surprising was the system did not actually crash, it was effectively a meltdown, but servers were still operational with load averages > 100. I was impressed with the ability for Linux to still (just) function.

parallel-ssh -o StrictHostKeyChecking=no -o ConnectTimeout=5 -i -h   uptime
 18:01:00 up 18:44,  0 users,  load average: 104.26, 110.03, 113.12
 18:01:00 up 18:56,  1 user,  load average: 62.33, 87.75, 90.40
 18:01:03 up 18:44,  0 users,  load average: 105.28, 115.33, 115.61
 18:01:03 up 18:44,  0 users,  load average: 149.35, 155.74, 133.68
 18:01:03 up 18:51,  0 users,  load average: 124.63, 121.31, 115.91
 18:01:03 up 18:44,  0 users,  load average: 118.99, 109.92, 110.60
 18:01:04 up 18:44,  0 users,  load average: 121.73, 118.40, 113.50
 18:01:04 up 18:44,  0 users,  load average: 113.89, 120.56, 114.64
 18:01:05 up 18:44,  0 users,  load average: 119.30, 119.71, 115.65
 18:01:05 up 18:44,  0 users,  load average: 126.33, 120.33, 119.02
 18:01:05 up 18:44,  0 users,  load average: 117.47, 113.01, 112.84
 18:01:05 up 18:44,  0 users,  load average: 172.21, 158.62, 135.19
 18:01:05 up 18:44,  0 users,  load average: 115.81, 114.96, 116.18
 18:01:05 up 18:44,  0 users,  load average: 122.25, 115.32, 115.27
 18:01:05 up 18:44,  0 users,  load average: 164.13, 168.04, 153.03
 18:01:05 up 18:44,  0 users,  load average: 123.80, 114.94, 110.29
 18:01:06 up 18:44,  0 users,  load average: 173.64, 173.80, 158.76
 18:01:06 up 18:44,  0 users,  load average: 132.52, 140.94, 135.43
 18:01:06 up 18:44,  0 users,  load average: 166.17, 151.68, 135.23
 18:01:06 up 18:44,  0 users,  load average: 170.14, 164.03, 145.31

The AWS m1.medium is a single CPU instance.

$ cat /proc/cpuinfo
processor	: 0
vendor_id	: GenuineIntel
cpu family	: 6
model		: 45
model name	: Intel(R) Xeon(R) CPU E5-2650 0 @ 2.00GHz
stepping	: 7
cpu MHz		: 1800.000
cache size	: 20480 KB
fpu		: yes
fpu_exception	: yes
cpuid level	: 13
wp		: yes
flags		: fpu de tsc msr pae cx8 cmov pat clflush mmx fxsr sse sse2 ss ht syscall nx lm up rep_good aperfmperf unfair_spinlock pni pclmulqdq ssse3 cx16 sse4_1 sse4_2 x2apic popcnt aes hypervisor lahf_lm arat epb xsaveopt pln pts dts
bogomips	: 3600.00
clflush size	: 64
cache_alignment	: 64
address sizes	: 46 bits physical, 48 bits virtual
power management:

Setting up a Virtual IP address (VIP)

by

These instructions are for CentOS/Redhat Linux distributions.

1. Identify your current NIC’s and IP addresses in use.

$ /sbin/ifconfig
eth0      Link encap:Ethernet  HWaddr 00:30:48:98:9C:A6
          inet addr:192.168.53.201  Bcast:192.168.53.255  Mask:255.255.255.0
          inet6 addr: 0080::230:48ff:fe98:9ca6/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:6159779 errors:0 dropped:0 overruns:0 frame:0
          TX packets:6137085 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:100
          RX bytes:1158210510 (1.0 GiB)  TX bytes:541617489 (516.5 MiB)
          Memory:e8000000-e8020000

lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:3791468208 errors:0 dropped:0 overruns:0 frame:0
          TX packets:3791468208 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:740660664181 (689.7 GiB)  TX bytes:740660664181 (689.7 GiB)

Determine which NIC you want the VIP on, in this case eth0 (the private address). We want to add the address 192.168.53.220

$  echo "DEVICE=eth0
BOOTPROTO=static
BROADCAST=192.168.53.255
IPADDR=192.168.53.220
NETMASK=255.255.255.0
NETWORK=192.168.53.0
ONBOOT=yes" > /etc/sysconfig/network-scripts/ifcfg-eth0:0

$ /etc/sysconfig/network-scripts/ifup-aliases eth0

Check your /sbin/ifconfig and now you should have a virtual IP address.

$ /sbin/ifconfig
eth0      Link encap:Ethernet  HWaddr 99:30:48:98:9C:A6
          inet addr:192.168.53.201  Bcast:192.168.53.255  Mask:255.255.255.0
          inet6 addr: 0080::230:48ff:fe98:9ca6/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:6159779 errors:0 dropped:0 overruns:0 frame:0
          TX packets:6137085 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:100
          RX bytes:1158210510 (1.0 GiB)  TX bytes:541617489 (516.5 MiB)
          Memory:e8000000-e8020000

eth0:0    Link encap:Ethernet  HWaddr 99:30:48:98:9C:A7
          inet addr:192.168.53.220  Bcast:192.168.53.255  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          Memory:e8100000-e8120000

lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:3791468208 errors:0 dropped:0 overruns:0 frame:0
          TX packets:3791468208 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:740660664181 (689.7 GiB)  TX bytes:740660664181 (689.7 GiB)

What's new in MySQL 5.4.1

by

Absolutely nothing?

5.4.0 was released with a change in the MySQL Binary distributions, delivering only 1 64bit Linux platform and two Sun Solaris platforms. This was officially announced on April 21 2009 however the 5.4.0 Release Notes state 05 April 2009. So it’s not a big deal, but consistency would be nice.

I’ve seen in a few posts 5.4.1, so I decided to try it out. Spending the time to read what’s changed in 2 months with the 5.4.1 Release Notes before I go downloading and installing, you read.

This release does not differ from 5.4.0 except that binary distributions are available for all MySQL-supported platforms.

Is this going to be the new policy from Sun? Release for Solaris platforms first, then later release for other platforms?

Getting wireless working on Ubuntu Macbook

by

I run Ubuntu 9.04 Januty on my Macbook. Previously installing Ubuntu 8.10, wireless worked automatically, for 9.04 it did not.

This is what I did to fix it.

  1. Verify your Macbook is seeing the Broadcom controller. See below for the lspci command, and expected output.
  2. Goto System -> Administration -> Hardware Drivers. The Broadcom STA wireless driver is activated, deactivate it.
  3. Add to /etc/modules a line with wl
  4. Reboot
  5. Goto System -> Administration -> Hardware Drivers. Activate the Broadcom STA wireless driver.
  6. Reboot
  7. Wireless now operational.
$ lspci
...
02:00.0 Network controller: Broadcom Corporation BCM4328 802.11a/b/g/n (rev 03)
03:00.0 Ethernet controller: Marvell Technology Group Ltd. Marvell Yukon 88E8058 PCI-E Gigabit Ethernet Controller (rev 13)
04:03.0 FireWire (IEEE 1394): Agere Systems FW323 (rev 61)

For reference, modprobe wl does not return any output in my environment, yet wireless works fine.

References: