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I'm using OS X Mavericks and just got a new external hard disk. I don't need to share it with a PC (so no need for FAT) but I do want it to have better I/O performance.

I'm a bit confused by the options:

  • Journaled
  • Journaled, Encrypted
  • Case sensitive, Journaled
  • Case sensitive, Journaled, Encrypted

Which one should I use? Thanks.

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  • Modern machines have a lot of memory for disk caching. This mean that typically the limitation is the native speed of the drive, not the file system. If speed really matters to you, get a SSD disk.
    – Thorbjørn Ravn Andersen
    Mar 4, 2018 at 21:26

2 Answers 2

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None of the HFS flavors will offer any performance benefit that's measurable. For that reason, go with the default format disk utility gives you and look to optimize elsewhere.

I have seen encryption slow down some storage medium such as slow USB flash and I would expect journaling there to also be more of a slowdown than on storage with fast cache or more responsive write service times.

I suppose journaling could in some rare circumstances (bizarre edge cases) slow things down as you need to journal certain actions, take the action, and then journal that the action is complete. However, the journaling is for rare events like file creation, file deletion, etc... - some metadata operations are journaled, not all data writes like other filesystems allow which can cause a large performance impact.

Journaling does make it easy to roll the filesystem back to a known state if the system crashes or the drive gets disconnected without changes flushed, so you can save hundreds of seconds to several minutes at the next reboot / mount by journaling.

For best performance, keep the drive approximately 70% full at most as portions of the disk are much slower for random access and the OS uses the fast part of the drive first.

So, in order of fastest to slowest speed transfer:

Connection type: Thunderbolt2 > Thunderbolt > Fiber Channel > SAS > USB 3.0 > FW 800/400 > USB 2.0

Storage Medium: Specialized SLC/MLC Flash with high speed controllers > PCI Prosumer SSD > 15k HDD > Consumer SSD > 10k/7.5k HDD > Fast Small FLASH > 5k HDD > Consumer USB flash storage

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  • So, in summary, none of the four mentioned in my question make a non-trivial difference? I guess I'll just use journaled option but not encrypted and case sensitive option. There is no "non-journaled" option in MAC OS disk utility.
    – clwen
    Jan 7, 2014 at 16:27
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Journaled for certain. I'd use the encryption option for security sake, but I don't know what the I/O performance trade off is with this setting. That is all.

For better I/O performance from external disks, purchase a RAID. I use 2 Guardian Maximus RAID boxes from OWC which provides a mirrored (redundant disk) RAID1, but they also sell other RAID boxes with faster I/O.

For true I/O performance, nothing beats SSD, though.

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    Journaled filesystems are certainly not faster in practice as a non-journaled FS. On HFS+ specifically, the difference is very minor, but when the disk is in actual use, journaling is either no faster to three times slower (say in a crazy case where all actions are journaled at the same time the disk is IO bound). The rest of the answer is gold in general. Pick multiple drives and SSD to get better speed and not HFS flavors.
    – bmike ♦
    Jan 7, 2014 at 3:26
  • RAID1 also does not offer any performance improvement. It is used for redundancy and data protection. Even RAID0 doesn't offer near the performance boost that is written on paper. Also, @bmike's right, journaling has no bearing on speed. It is used more for error recovery and to protect against data corruption.
    – user10355
    Jan 7, 2014 at 12:20
  • So, in summary, just use Journaled, but not encrypted and case sensitive option?
    – clwen
    Jan 7, 2014 at 16:26
  • Yes. You have distilled our answers succinctly.
    – IconDaemon
    Jan 7, 2014 at 22:33

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