Disk on Evan Hoffman

Macbook Pro locks up with SSD installed.

Tue, 23 Aug 2011 12:04:54 +0000

A few weeks ago I switched from my trusty old HP nc8430 to a Macbook Pro (MC118LL/A) that was left spare when another employee left. I mostly enjoyed using Linux but I was tired of dealing with weird quirks like having X lock up, essentially forcing me to do a hard reboot.

To transition, I copied my documents from Linux to Mac, then turned off the Linux laptop. Surprisingly I found I didn’t need to turn Linux back on at all. Last week, I decided to put the final nail in Linux’s coffin by taking the SSD (Corsair CMFSSD-128GBG2D)out of it and putting it in my Macbook. The Macbook was pretty fast (Core 2 Duo @ 2.5 GHz) but some things were noticeably slower on its 7200RPM disk than on Linux with an SSD, especially running Windows VMs.

Benchmarking disk IO on ext3 vs ext4 vs xfs with fio

Fri, 22 Jul 2011 07:15:05 +0000

With the old database phased out, I figured this was a good time to benchmark IO on it before either repurposing it or mothballing it. In the past I’ve used dd for elementary sequential read/write testing, but I recently found fio which is much more versatile. Apparently developed by FusionIO, fio lets you control concurrency, blocksize and many other parameters and reports lots more data, most notably IOPS.

I created 4 fio config files, basically the same as the one below, for direct / buffered disk access and sequential / random writes. All have 8k blocksize since that’s what Postgres uses by default.

How I fixed my Wii's noisy disc drive & read errors.

Fri, 25 Feb 2011 00:10:31 +0000

I got my Wii in late 2006 and around 2009 I noticed it was starting to sound like a circular saw when the disc drive was spinning. This was annoying but it didn’t affect the games so I never thought much about it.

About two weeks ago, however, New Super Mario Bros. Wii stopped working:

The Wii basically worked except for the disc drive. As soon as I put a disc in, I’d get the error above - even if I didn’t start start the game. I tried blowing in the disc slot (the only thing I could think of… worked for my old NES!) but the problem continued. I figured I had two choices: buy another Wii or attempt to fix mine. Since mine was already essentially useless I figured it couldn’t hurt anything to try fixing it.

The VMware datastore LUN 2TB (well, 1.99999 TB) size limit

Fri, 24 Sep 2010 16:00:15 +0000

I started migrating our physical machines to VMs using VMware a few years ago and the first problem I ran into is still the most annoying one: the size limit for LUNs is, per VMware’s docs, (2TB - 512B). That’s 512 bytes shy of 2TB, so basically 1.99999 TB, or 2047.999 GB. So when I create a new LUN for a datastore in the SAN the max size is 2047 GB. Now, as the VMware KB article states, this is a limitation of SCSI, not VMware per se, but that doesn’t make it any less annoying. When I first setup ESX, I created a 5 TB LUN for the datastore. It showed up in vCenter as 1 TB. After some Googling I learned of the 2 TB limit – the usable space is basically usable space = (size of lun) % 2TB, where % is the modulo operator – and found something suggesting using extents to expand the datastore across luns. I did that, but I later learned that there seems to be a consensus that extents should be avoided.

The bright side of Compellent

Wed, 22 Sep 2010 16:07:46 +0000

Since I was bemoaning Compellent’s pricing recently I figured it would be unfair of me not to highlight the upside. Their tagline is (or was when we purchased it) “The only SAN so sophisticated it’s simple.” While I can’t say whether they’re the ONLY one, the idea is definitely true. This is the first SAN I’ve ever used, and aside from the learning curve for iSCSI itself (targets, spinup delay, etc.) it’s totally simple and intuitive. Create LUNs, map them to servers. Don’t worry about things like RAID levels or hot disks. We’re into our second year with Compellent and it’s definitely lived up to its promise of simplicity.

Oh, Compellent... again with the disk prices.

Wed, 25 Aug 2010 00:57:04 +0000

Time to expand the SAN again.

I planned and budgeted for this this year but it still pisses me off. Look, I realize these guys have to make money, but the bottom line is they’re charging over $1.40/GB for SATA storage. There are 7200 RPM 2TB SATA drives on Amazon and Newegg ranging in price from $130 to $220. That’s as low as $0.065/GB. There was even a 2TB WD “Green” drive (sub-7200 RPM, I think 5900 RPM) on Slickdeals today for $99. That’s 5 cents per gig.