Category Archives: Uncategorized

General blog posts

Replacing a failed zpool ZFS drive

We have a Sun X4500 ‘Thumper’ that recently had a failed drive. Our zpools are all raidz2 with 4 spares. We were getting errors on the disk c1t5d0, although the drive hadn’t failed completely.

As we had not yet tested replacing a ‘live’ drive the disk was pulled from the system before running any commands to remove it from the pool.

You can run the following command to see the status of your pools –

zpool status

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Blackberry/Google calendar only synching "Default Calendar"

I love my new Blackberry Curve! I had a small problem setting up the Google Calendar Sync and thought this might help someone else.

I had no problem installing the software from http://m.google.com/sync – just point your Blackberry web browser at that URL.

However, when I logged in and tried to sync my calendars (I have 5 different calendars setup) I only saw “Default Calendar” listed under “My Calendars”.

It turns out this was because I was logging in to Google Sync using a secondary e-mail address I have assigned to my Gmail account (ie I was logging into Google Sync using [email protected] rather than [email protected])

When I logged in to Google Sync using my Gmail username ([email protected]) all of my calendars were listed under options after the initial sync.

ERROR: Could not open file (/a/etc/vfstab)

I was trying to install Solaris U5 on one of our Sun boxes using jumpstart today and came across the error –

ERROR: Could not open file (/a/etc/vfstab)

We were previously using Solaris U4 and I had copied the U5 media to our jumpstart server. What I had forgotten to do was to copy the x86.miniroot file from the installation media to where it was being loaded from.

This resulted in the U5 installation trying to use the U4 ramdisk image. Doh!

So, if you see the same error, it’s something to check.

What does my website look like?

So, maybe everyone knows this already, but …

I’ve only just started started designing websites and found this useful site – http://browsershots.org/

It will show you what your website looks like when viewed in different browsers, on different platforms. It actually shows you a screen grab of the page.

Turns out IE5.5 doesn’t like my transparent png, nor does it like something in my stylesheet!

What to consider when you’re looking for a VPS?

Here are several areas you should consider when looking for a VPS – I’m sure there are others! Please let me know if you think of any and I’ll add them to the list

Memory: When I first started looking for a VPS I was shocked at how little memory you got. 256MB sounds like a ridiculous amount – however, you have to remember that a lot of the memory that the Linux kernel is using does not come out of your allocation. Also, programs these days expect there to be a lot of memory available on the server. If you’ve only got a small amount then you can tweak the configuration files (of apache, mysql, etc …) to use less memory. Sometimes this will degrade performance to an unacceptable level but often not.

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What is a Virtual Private Server (VPS)?

Virtual Private Server (VPS) or Virtual Dedicated Server (VDS) are two terms that describe the same thing – a share (or slice) of a physical server. VPS’s are becoming very popular amongst web hosters and developers who’s sites requirements are greater than a shared hosting supplier can provide, but do not yet demand their own dedicated server.

With shared hosting you get some web space that you can run your site on, however, problems can arise if your site is too busy (it can affect other users with that shared hosting provider) or, if the software that you want to run (mailserver, web blog, picture gallery, bulletin …) has certain requirements that a shared hosting provider does not provide.

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ZFS: The future of filesystems?

ZFS is the (relatively) new filesystem from Sun with some fascinating properties. Here are some headline facts just to get your attention – the maximum size of a single file on a zfs filesystem is 16 ExiBytes (that’s 1000 million gigabytes), it’s possible to take a complete filesystem backup (snapshot) in a few seconds and you’ll never have to fsck your filesystem again to make sure it’s not corrupt.

So, sounds pretty impressive, heh? So what makes all this possible?

There are 3 main components to zfs that enable a lot of the cool functionality. If you’ve used a NetApp OnTap based filer before then these will sound familiar (hence, Netapp and Sun’s lawyers getting in a bit of overtime).

The first component is the Copy On Write transactional model (COW). This means that when a block of data on the filesystem changes it is not overwritten, a new block is created and the metadata for the file that has changed is updated.

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