Does It Matter How Your USB Flash Drive Is Formatted?

When you buy a USB flash drive, it comes preformatted for use on Window PCs. But will it work more efficiently if its reformatted in a Mac-native format? We just had to find out.

minion flash drivesI was in a local outlet store a while back, and they had 8 GB USB flash drives for just $1.50 each. I should have bought all of them, but I only grabbed four. When I went back a few days later, none were left.

Okay, the flash drives do look like the minions from Despicable Me 2, but for $1.50, they were a steal. (It’s also easy to remove the flash drives from the minions if the yellow guys embarrass you.)

The flash drive itself appears to be sourced from PNY, a brand you’ll often find in stores. Other than capacity and the fact that it’s a USB 2.0 device, I haven’t been able to find any more technical specifications.

Round 1: PowerPC – Power Mac G5

Minion flash drive

For the first set of tests, I plugged the drive into the USB 2.0 port on the front of my 2.3 GHz Power Mac G5 Dual and ran Xbench 1.3 under OS X 10.5 Leopard. For the second test, the flash drive was formatted as Mac OS Extended (Journaled) but with the partition still in Master Boot Record (MBR) format. For the third test, I repartitioned the drive using the APM option. Here are the results (higher numbers are better):

Format:                           FAT   Mac MBR   APM    GUID
Disk Test                         0.31    0.32    0.28   0.28
  Sequential                     10.18    9.73    9.07   8.47
    Uncached Write, 4K blocks     7.05    6.54    5.85   5.53
    Uncached Write, 256K blocks   6.68    6.71    6.35   5.83
    Uncached Read, 4K blocks     14.86   13.55   12.54  11.47
    Uncached Read, 256K blocks   29.22   28.44   30.33  30.43
  Random                          0.16    0.16    0.14   0.14
    Uncached Write, 4K blocks     0.04    0.04    0.04   0.04
    Uncached Write, 256K blocks   0.84    0.80    0.72   0.71
    Uncached Read, 4K blocks    466.43  520.94  565.57 325.25
    Uncached Read, 256K blocks   80.35   76.98   77.72  78.19

Overall, not a whole lot of difference. Sequential reads and writes are a bit faster in general, with Mac format having a very slight advantage in two of the eight drive tests. I’d call it a wash.

Maximum read speed is 15.3 MB per second. That translates to 122.4 Mb per second, which is far, far below the 480 Mb per second bandwidth of USB 2.0. The implementation of USB on PowerPC Macs just doesn’t hold up compared with Intel-based hardware.

Round 2: Intel – Core 2 Duo Mac mini

The second set of tests were run on my 2.0 GHz 2007 Mac mini with OS X 10.6.8 Snow Leopard. The flash drive was plugged into a USB 2.0 port in my monitor, since accessing the rear of the Mac mini is quite difficult with my current setup.

Format:                           FAT    ExFAT    APM    GUID
Disk Test                         0.32                    0.29
  Sequential                     12.78   12.25   12.24   11.31
    Uncached Write, 4K blocks     8.64    7.96    7.70    7.63
    Uncached Write, 25K blocks    8.11    7.96    8.15    7.13
    Uncached Read, 4K blocks     18.04   17.58   18.19   18.30
    Uncached Read, 256K blocks   53.94   54.51   52.26   36.11
  Random                          0.16            0.15    0.15
    Uncached Write, 4K blocks     0.04    0.04    0.04    0.04
    Uncached Write, 256K blocks   0.83    0.84    0.77    0.79
    Uncached Read, 4K blocks    698.27  654.57  694.73  694.54
    Uncached Read, 256K blocks  135.30  130.45  130.60  131.33

As on the Power Mac G5, the flash drive generally performs at its best using its standard FAT formatting. The loser appears to be GUID, which only took top honors in one of eight tests. Still, overall, you probably won’t notice a difference when saving or reading files. By sticking with FAT, you assure that Windows and Linux PCs can work with the drive.

The best read results were 27.40 MB per second, 219.2 Mb per second. Intel-based Macs have a real edge in USB 2.0 performance vs. PowerPC, but even then these flash drives don’t achieve half the bandwidth of USB 2.0. (For the record, individual USB devices are limited to about 2/3 of bandwidth, so the Minion flash drives reach almost 2/3 of their potential.)

Round 3: Intel – Core 2 Duo MacBook

The third set of tests were run on my 2.0 GHz Late 2008 Aluminum MacBook with OS X 10.9.5 Mavericks. The flash drive was plugged into the frontmost USB 2.0 port.

Format:                           FAT    ExFAT    APM    GUID
Disk Test                         0.32                    0.29
  Sequential                     12.78   12.48   12.47   11.73
    Uncached Write, 4K blocks     8.85    7.86    9.21    8.11
    Uncached Write, 25K blocks    7.77    8.26    7.21    7.17
    Uncached Read, 4K blocks     18.47   18.74   18.33   16.86
    Uncached Read, 256K blocks   52.45   53.66   52.88   53.31 
  Random                          0.20    0.19            0.18
    Uncached Write, 4K blocks     0.05    0.05    0.05    0.05
    Uncached Write, 256K blocks   0.82    0.85    0.78    0.79
    Uncached Read, 4K blocks    700.10  666.01  319.19  711.96
    Uncached Read, 256K blocks  130.68  129.58  137.21  131.16

Of the three setups tested, this is the only one to achieve a score higher than 0.04 on the 4K block uncached random writes – hands down the slowest test in the Xbench benchmark suite.

Best throughput this time was 26.97 MB per second, just a bit slower than on the Mac mini with OS X Snow Leopard. ExFAT has a slight edge over FAT, but you probably won’t see any difference in the real world so you may as well leave the flash drive in its original FAT format.


Seriously, you don’t buy a novelty flash drive for speed. You buy it for convenience and cuteness – or just because they’re dirt cheap on clearance. Still, it’s been an interesting experiment – and a reminder of the poor USB performance we left behind when Apple ditched PowerPC for Intel in 2006.

Keywords: #flashdrivespeed #flashdriveperformance #flashdriveformat #flashdrivebenchmark #usbthroughput

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