Tag

linux Archives - AWS Managed Services by Anchor

Bugfixing KVM live migration

By | Technical | 2 Comments

Here at Anchor we really love our virtualization. Our virtualization platform of choice, KVM, lets us provide a variety of different VPS products to meet our customers’ requirements. Our KVM hosting platform has evolved considerably over the six years it’s been in operation, and we’re always looking at ways we can improve it. One important aspect of this process of continual improvement, and one I am heavily involved in, is the testing of software upgrades before they are rolled out. This post describes a recent problem encountered during this testing, the analysis that led to discovering its cause, and how we have fixed it. Strap yourself in, this might get technical.

Read More

Round ’em up with Jessie

By | Technical | No Comments

A new version of the Debian operating system, version 8 (codename “Jessie”) was released over the weekend. Just as we did two years ago with Wheezy, we are now immediately offering Debian Jessie as an option for new customers. This includes our new OpenStack infrastructure, where Jessie is our recommended option for Managed Operations and Unmanaged instances. If you already have a Debian server with us and would like to upgrade, drop us a line and we’ll be able to advise as to what’s involved to support your stack on Jessie. To find out more about the services we can offer, visit http://www.anchor.com.au/.

Read More

Awesome but often unknown Linux commands and tools

By | Technical | 5 Comments

I’ve been working in this industry for a while now and naturally spend a lot of time using Linux on a daily basis. This gives lots of exposure to various Linux commands and tools. That said, I am sometimes surprised when I see, often very experienced system administrators, using somewhat convoluted commands to do something relatively simple using a different tool. This is my opportunity to share some of these experiences: 1. pgrep and pkill – The first command ‘pgrep’ will return the process id based on a name or other attributes. pkill will signal a process with a matching name or attribute. Want to kill all processes being run by a given user? Issue a pkill -U USERNAME; sure beats the hell out of: ps -U USERNAME | awk…

Read More

Evil hack to make arrow and SysReq keys work with a Dell iDRAC KVM and Linux desktop

By | Technical | 4 Comments

So you’re trying to use the arrow keys in a remote server console with the iDRAC KVM. The keys not working and it’s driving you mad? Or perhaps that mission critical server is experiencing pain and you need to make use of the magic sysrq key to debug it? Unfortunately, for a long long time, this has not worked if you are using Linux on your desktop. Making it work Just follow the steps below and you should be good to go. Download idrac.tar and unpack it: wget http://www.anchor.com.au/blog/wp-content/uploads/2011/03/idrac.tar tar xvf idrac.tar Build and install it: cd idrac make make install All done! It should take effect the next time you launch a virtual console. If you want to make use of magic SysReq, make sure that it is disabled on…

Read More

Secure encrypted storage for your hosted server, VM, VPS, cloud server or $BUZZ_WORD

By | Technical | 2 Comments

So you’ve just provisioned your shiny new OS instance with your host of choice, loaded in your confidential data and away you go without a worry in the world right? If your data consists only of captioned photos of cute furry animals, then all is well. Perhaps however, your data is worth just a wee bit more than that (not that we don’t ♥ cute furry animals!). Depending on your host and product used, your data could be sitting on anywhere from locally attached disks, a NAS/SAN or some clustered distributed block device/filesystem with no way to easily determine who has access to it, what snapshots exist, what will happen to failed media, etc. For certain customers with certain sensitive applications, that is simply not an acceptable risk. To protect your data…

Read More

Reduce Linux VPS/VM guest memory usage

By | Technical | 3 Comments

Reducing the memory usage in your VPS/VM can be a great way to free up some resources to handle more requests, users or some other metric of win. By default at Anchor we provision our Red Hat & Cent OS VPS servers with a trim memory usage profile by disabling a lot of unneeded services at install time. We do this by using Trogdor (our hardware/software burninator) and Puppet. So just what services do we disable, if they exist on the new VPS? gpm netfs pcmcia sgi_fam yum-updatesd pcscd rhnsd xfs hald hcid or sdpd hpiod or hpssd.py dbus-daemon cupsd You can also reap performance gains by changing how you serve content. For example you can use a cut down high performance web server (nginx or lighttpd) to serve all…

Read More

VMware ESX Guest Disk IO

By | Technical | No Comments

Knowing the state of your disk IO latency in VMware ESX can help you pre-empt performance & capacity issues before the occur. There are a few guidelines you should keep in mind. These notes are directed towards people using directly attached storage. Write latency should be 0, because you have that fancy battery backed controller caching writes, right? Read latency should be under 8ms. Use the smallest stripe size possible for your RAID array setting. This helps keep random IO performance acceptable at the cost of some sequential performance. Do not virtualise very heavy random IO workloads on shared arrays, other guest VMs wont like you for it. Unless you have a very compelling reason not too, use RAID 10. Some other notes, specific to Linux guests are: Mount file…

Read More

Awesome Linux tool of the day: dstat

By | Technical | No Comments

What is dstat?  dstat is a versatile replacement for vmstat, iostat and ifstat. Dstat allows you to view all of your system resources instantly. Eg, You can compare disk usage in combination with interrupts from your HDD controller, or compare the network bandwidth numbers directly with the disk throughput (in the same interval). No blog post pimping a cool tool would be complete without the obligatory screen shot.

Read More