March 2008 Archives

In 10.5 and 10.5.1 there was a bug that’d make my iDisk explode to take all available space, yikes. Fortunately that has been fixed now (not that I use the iDisk much anymore - hello JungleDisk!).

It doesn’t seem like the iDisk disk images get compacted automatically to take less space if you delete files, so what I learned from the bug is generally useful.

You can compact a “sparse” disk image manually from the Terminal application.

The iDisk can’t be in use, so close any files opened on it. Then open a terminal and run:

hdiutil unmount ~/Library/FileSync/*/*.sparsebundle
hdiutil compact ~/Library/FileSync/*/*.sparsebundle

The hdiutil compact feature also works on old fashioned sparse disk images (all data in one file versus the “sparsebundles” that are really directories with lots of smaller files). I used it to reclaim a few gigabytes from some old disk images, yay.

It looks like my tutorial is almost sold out (and so are several of the others already!)

So if you're planning to go to the MySQL conference, don't delay - go sign up!

We got a couple of new servers at Solfo recently which showed me one of the reasons virtualization is so popular now: Servers are too fast!

The "standard issue" CPU is now a quad-2.5GHz CPU, so in each server we have 20 GHZ CPU and 32GB ram (at less than $50 per gigabyte it's too cheap to not just fill it up and be done upgrading). Just a few years ago the CPUs we were getting were "only" dual 2GHz, for ~8GHz CPU per box. That's a big increase!

In each "tier" of the application (app servers, db servers, search servers) our main reason for having more than one or two servers is redundancy / high availability - never lack of CPU and rarely because we need more memory.

Here's from one of our webservers (virtualized with Xen with 6 of the 8 CPUs on the "real" hardware).

The big exception is the MySQL servers where we get constrained by I/O so we need a single chassis with lots of disks (the $$ version would be to get external enclosures or SAN boxes with disks) and of course in the MySQL servers we can easily use all 32GB ram.

Anyway, the conclusion: Please give us cheaper, lower power CPUs. More memory, sure - we'll figure out to use it. More disk I/O: yes, please! More more more! Faster CPUs makes sense at scale, of course, but for a smaller website with just a handful of million visitors a month we just can't make a dent in the available CPU. Maybe if we used Ruby instead of Perl. ;-) (just kidding).

(I realize that AMD and Intel makes plenty "slow" CPUs, but they don't come in server boxes with fast I/O and all that).