On the heels of my previous post on StackOps and OpenStack, I thought I would quickly share two of the most valuable links that I came across in my search for good ‘getting started’ documentation.

First, this link provides an excellent architectural overview of OpenStack, which can be quite confusing initially, if you are not a regular user of Amazon EC2 type cloud services.

Secondly, CSS Corp’s beginner’s guide provides an almost invaluable resource to anyone who is getting started and wants access to very easy to read and well written documentation on the subject.

Ok I just found this video of Chris Mason giving a talk on Btrfs at Linuxcon 2010.  It appears to be very similar to the webcast I linked to  a few days ago, hosted on Oracle.com.  This video however is hosted on linuxfoundation.org and there is no registration required which is nice.

KQ Infotech has released (currently in closed beta) code that brings ZFS to Linux via a loadable kernel module.

Here is a link to the current and future feature set.  The reason that this is exciting is that although other ZFS implementations for Linux have traditionally existed, each of the available options have significant drawbacks.  For example  ZFS-FUSE is  implemented in userspace using FUSE, which has additional overhead due to the context switching that is required while switching back and forth between kernel-space and user -space. .

Another option is ZFS on Linux which provides a stable SPA, DMU and ZVOL layer, but does not however provide a Posix layer (ZPL) that would enable you to actually mount a ZFS filesystem from inside Linux.  From what I understand, KQ Infotech has basically taken some of the ZFS on Linux code that was developed by the Lawrence Livermore National Laboratory (LLNL), and actually implemented  the missing ZPL layer.

NPR was recently accepted into the closed beta program,  and I took some time last week to get this module installed on a Dell Poweredge 2950 running a 64 bit version of Ubuntu 10.04.  We are currently testing ZFS under  kernel version  2.6.32-24.  I have not had a ton of time to test things out, but I would say so far so good.  I plan on posting some ZFS and Btrfs benchmarks in the next few weeks after I get some time to better test performance, throughput, etc.

While doing research into poor write performance with Oracle I discovered that the server was using the LSI SAS1068E. We had a RAID1 setup with 300GB 10K RPM SAS drives. Google provided some possible insight into why we the write performance was so bad(1 2). The main problem with this card is that there is no  battery backed write cache. This means that the write-cache is disabled by default. I was able to turn on the write cache using the LSI utility.

This change however did not seem to any difference on performance.  At this point I came to the conclusion that the card itself is the blame.  I believe  that this is an inexpensive RAID card that is good for general use of RAID0 and Raid1, however for anything were write throughput is important, it might be better the spring for a something a little bit more expensive.

When it was all said and done we ended up replacing all the these LSI cards with Dell Perc 6i cards.  These cards did come battery backed…which allowed us to then enable the write cache, needless to say the performance improved significantly.

Welcome to shainmiley.com. I plan to use this blog to discuss some of the technological issues that I encounter on a day to day basis.  Topics will include Linux, scaling infrastructure, cloud computing, Mysql, open source,  storage etc.