Matt Connolly's Blog

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ZFS performance networked from a Mac

Before I go ahead and do a full time machine backup to my OpenSolaris machine with a ZFS mirror, I thought I’d try and test out what performance hit there might be when using compression. I also figured, that I’d test out the impact of changing the recordsize too. Optimising this for the data record size seems to be best practices for databases, and since Time Machine stores data in a Mac Disk Image (SparseBundle) it probably writes data in 4k chunks matching the allocation size of the HFS filesystem in the disk image.

There were three copy tasks done:

  1. Copy a single large video file (1.57GB) to the Netatalk AFP share,
  2. Copy a single large video file (1.57GB) to a locally (mac) mounted disk image stored on the Netatalk AFP share,
  3. Copy a folder with 2752 files (117.3MB) to a locally (mac) mounted disk image stored on the Netatalk AFP share.

Here’s the results:

To Netatalk AFP share To Disk Image stored on AFP share To Disk Image stored on AFP share
ZFS Recordsize and compression 1 video file, 1.57GB 1 video file, 1.57GB 2752 files, 117.3MB
128k, off 0m29.826s

53.9MB/s

2m5.889s

12.7MB/s

1m45.809s

1.1MB/s

128k, on 0m52.179s

30.9MB/s

1m36.084s

16.7MB/s

1m34.367s

1.24MB/s

128k, gzip 0m31.290s

51.4MB/s

2m32.485s

10.5MB/s

2m29.141s

0.79MB/s

4k, off 0m27.131s

59.3MB/s

2m16.138s

11.8MB/s

2m47.718s

0.70MB/s

4k, on 0m25.651s

62.7MB/s

1m59.459s

13.5MB/s

1m41.551s

1.2MB/s

4k, gzip 0m30.348s

53.0MB/s

5m16.195s

5.08MB/s

4m48.378s

0.41MB/s

I think there was something else happening on the server for the 128k compression=on test, impacting on its data rate.

Conclusion:

The clear winner is the default compression and default record size. It must be that even my low powered Atom processor machine can compress the data faster than it can be written to disk resulting in less bandwidth to disc and therefore increasing performance at the same time as saving space. Well done ZFS!

One response to “ZFS performance networked from a Mac

  1. Pingback: My first real Time Machine backup on a ZFS mirror « Matt Connolly’s Blog

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