Sunday, December 28, 2008

Datacenter Capacity Planning

A lot needs to be considered when planning for a datacenter. Power, cooling, UPS, generators, rack space, cost. All these come into play.

Here are a few links to some vendor calculators I came across that has helped me.

DELL

HP

Monday, December 22, 2008

Displaying 32/64 rpms installed on a Redhat system

It's been a while since I've prepared an Oracle Linux server. Today I got handed a hot potato - "An Oracle Linux server with missing Libraries". This is often the case with oracles installer - It won't install without the proper libraries. What had happened was the previous sysadmin installed the 32bit versions of the libraries and Oracle was looking for the 64bit version. However, with Redhat's default rpm -qa command it often displays only the package but doesn't tell you the architecture of the package. Here's a neat command that would display the architecture of the installed package.

rpm -qa --queryformat "%{NAME}-%{VERSION}.%{RELEASE} (%{ARCH})\n"

Give this a try the next time you install a 64bit Redhat system.

Saturday, December 6, 2008

iSCSI @ Home

iSCSI or internet SCSI is a standard for running SCSI over an ip based network. For people familiar with this technology it basically enables you to mount remote disks over your existing IP infrastructure.

Today I setup a simple iSCSI mount on Linux for my local windows desktop at home over my home network. Lets start with the basic terminology and requirements.

You need a Linux box with plenty of storage space, preferably with RAID and a decent network connection - 1G acting as your SAN. This will be your iSCSI target.

Then you need a Linux or Windows desktop to act as your mount point - The iSCSI initiator.

Here are some links on the web which explains this more in detail
Setting up iSCSI in 5 mins
Enterprise iSCSI for Linux
Microsoft iSCSI iniator

Building a simple iSCSI was as simple as following those links and instructions and downloading the appropriate files.

In my quick and dirty implementation I didn't have a high performance disk setup nor a proper LVM setup to export my devices. However, the Linux Enterprise iSCSI target supports exporting files as a virtual file/block device. So I simply created an empty 10G file as my iscsi mount by using dd.

dd if=/dev/zero of=/tmp/iscsi-file bs=1M count=10240

I then exported the /tmp/iscsi-file as LUN0 in the ietd.conf file. It's as simple as that!

Setting up the Windows iSCSI initiator was as simple as eating lettuce.

Next, I'll be posting about setting up the Linux iSCSI initiator as that is a bit more complicated and may require more troubleshooting steps.

##Update
Someone recommended me to a more powerful open source tool for SAN,NAS,iSCSI.
It's called openfiler. Seems like an awesome tool!