File Systems – the state of Mac OS X data integrity

Welcome back to the D Revolution blog after a Christmas hiatus.
Sorry for the nerdy nature of the post – it’s often the underlying technology that propels computing forward.

Ten’s Compliment have a File System plugin for Mac OS X that allows the use of ZFS instead of the standard HFS+.

After a year of following a startup company full of ex Apple engineers, they have finally released a product.
Why would I care you ask?
Simply put, HFS+ dates back to 1998 (the year I stared D Revolution) and whilst it has served Apple well, it is missing vital features for a modern filesystem.
Namely, file integrity and scalability.
Whilst Apple have cleverly added features like hard links, hot zones, auto-defragmentation, meta-data journaling, compression and other features without breaking compatibility, it is not a particularly stable and recoverable file system.
With todays disks now up to 4TB and the massive explosion in the amount of data stored, there are a few critical things needed in a modern file system.

1. Data Integrity
HFS+ does not scrub disks looking for bad blocks or corrupt data – ZFS does.
That means ZFS can automagically recover files from non-function parts of a disk – which is actually a fairly common occurrence.

2. Snap Shots
HFS+ can not create disk snap shots which are like an on disk backup of data from a point in time – ZFS does.
That means, if you are backing up large amounts of data on OS X the underlying data can change during the course of a single backup if files are re-saved or left open.
With ZFS snapshots, you can simply backup the snapshot (snapshots are virtually instantaneous irrespective of size) with a completely frozen set of data.
A great side effect of this is you can do hourly snap shots (any of which an be restored) and backup the snapshots once a day to the backup device of your choice.

3. Pooling
HFS+ cannot pool drives together.
Pooling drives would allow for instance, Time Machine to backup to more than one destination drive, or creating effective software RAIDs.

I can’t recommend the Ten’s Compliment ZFS system yet for a few reasons.

1. You cannot share a ZFS volume over AFP – meaning it won’t work for your server storage (an obvious place to use it)

2. It is not bootable yet so you cannot protect your startup disk – making it useless for single disk system like the MacMini, iMac, MacBook Pro and MacBook Air.

I hope to test the system soon by installing an SSD in my MacBook Pro and using the default hard disk for bulk storage.
NOTE: There is a whole raft of products D Revolution will be teasing this year so stay tuned…

One comment

Comments are closed.