adchen's blog

Snow Leopard - still no ZFS

adchen — Fri, 17 Jul 2009 05:33:28 +0000

I know it's hardly news, but after the announcements at WWDC in June, it's apparent that Apple's upcoming Mac OS version 10.6 aka "Snow Leopard" won't have ZFS like everyone thought it would.

And with MacZFS stuck at build 119 and with still some potentially serious problems, I've kind of put my plans for any sort of major Mac ZFS setup on the backburner. Maybe 10.7? Who knows.

I guess the Drobo is looking better and better these days.

ZFS: Creating Mirrored Storage

adchen — Fri, 17 Jul 2009 05:25:23 +0000

Since we're focusing on redundant and protected storage, we're going to jump right in and talk about ZFS mirrors. We'll cover normal ZFS striping and concatenated storage shortly though.

The easy way to practice using ZFS is to use files as our virtual devices (vdevs). Normally vdevs are usually entire hard drives or large slices of them. But vdevs be just about anything, including files. For production purposes you'd never use files as vdevs, since they're layered on top of your operating system and subject to some performance overhead. Besides your vdevs would also be at the mercy of things that goes on in your file system (e.g.

Drobo Pro

adchen — Fri, 10 Apr 2009 07:15:59 +0000

Data Robotics, maker of the Drobo storage products has rolled out a nice looking high-end product that is essentially a double-wide Drobo, taking on up to 8 SATA drives:

Images courtesy of Drobo

The Drobo Pro has 8 drive bays and 3 ways of connecting to a host system: iSCSI, Firewire 800, USB 2.0.

With up to 8 drives, the Drobo now supports double-parity to survive the outright failure of 2 drives. With typical ZFS RAIDZ2 you'd need at least 5 drives (3 data + 2 parity) to support double-parity, so I'm going to assume you'd need at least 5 drives in the Drobo Pro as well for double-parity. Although technically they could default to mirroring, if you only had 4 drives, but that would cut usable space by half.

The Drobo Pro even comes with a rack-mount kit, although looks a little goofy with the 2 "wings". Seems like they could just fill it out to 12 drives across and make use of the dead space. Also, they don't list the depth of the unit, but I imagine it's relatively short compared to most rack-mount gear.

Mac ZFS Tip #1: Avoid Prompts for the Admin Password when Writing to ZFS volumes

adchen — Fri, 03 Apr 2009 13:15:11 +0000

Avoid Prompts for the Admin Password when Writing to ZFS volumes

When you're creating zpools and ZFS volumes you have to be doing it with root privileges, so naturally any volume you create is going to be owned by root. So if you are trying to write to these volumes as your normal Mac login, it's going to prompt for the admin password every time.

The easy fix is just to make yourself the owner of that volume:


# chown -R UserName:GroupName /Volumes/myzpool

If you have multiple users, then use chmod to allow access to other users.

Mac ZFS Annoyance #1: "Empty Trash" busted

adchen — Thu, 02 Apr 2009 19:15:50 +0000

Empty Trash won't work

Badness level, on a scale of 1 (not bad) - 100 (WTF?): 5

If you delete files on a ZFS volume via the Finder, you won't be able to use Empty Trash properly. The files don't show up in the Finder anymore, but they're actually just moved to a hidden directory called ".Trashes". You have to use "rm" in the Terminal to really remove the file (or just "rm -rf .Trashes").

As far as most things go, this is not a huge deal, but you could easily forget that this issue exists and accidentally let your zpool fill up over time and then waste a bunch of time troubleshooting it. Maybe some sort of Applescript/Automator/cronjob approach would provide a semi-seamless workaround.