Re: Flash memory formating - Mac/Windows?

paulfuchs@porkain'tkosher.oink (Paul Fuchs) writes:

Well, I did a couple of tests with the 4 GB flash on my G5 iMac in FAT
32. Copying mp3 files from my music folder, it ran at about 100 MB per
minute. Not going set any land speed records, but for my purposes and
uses, I can live with it. The OS X formatting didn't seem much quicker.

I decided to run some tests here. My flash drive is a Kingston 2GB
"Data Traveler 2.0" drive. It is attached to the USB 2.0 hub in my
display, which is attached to a Belkin USB 2.0 PCI card. The computer
is a dual 1GHz QuickSilver-2002 PowerMac G4. The system software is Mac
OS 10.4.10.

For the format test, I used Disk Utility. Timing is by stopwatch from
when I click "erase" in the confirmation dialog until the application
buttons re-enable. I estimate my thumb is accurate to within about 1-2
seconds.

The copy test is performed by copying a containing 500M of music files
via a terminal window. Timing is by the shell's "time" command:
time cp -R ~/Desktop/tmp /Volumes/Untitled

The read test is performed by catting all the files and dumping the
results in the bit-bucket. Timing is by the shell's time command:
time cat /Volumes/Untitles/tmp/* > /dev/null

The results of my tests are:

Mac OS Extended (Journaled)
Format: about 14 seconds
Copy 500M: 2:02.07
Read 500M:
1:23.98 - immediately after writing the files
0:02.32 - the second time after writing
0:44.68 - after an eject/re-insert
0:01.11 - the second time after the re-insert

Mac OS Extended (not Journamed)
Format: about 14 seconds
Copy 500M: 2:04.92
Read 500M:
1:29.63 - immediately after writing the files
0:02.39 - the second time after writing
0:47.34 - after an eject/re-insert
0:03.57 - the second time after the re-insert

UNIX file system
Format: about 2 minutes
Copy 500M: 6:30.18
Read 500M:
0:04.69 - immediately after writing the files
0:01.11 - the second time after writing
0:52.18 - after an eject/re-insert
0:02.55 - the second time after the re-insert

MS-DOS file system (FAT32)
Format: about 43 seconds
Copy 500M: 3:29.45
Read 500M:
0:01.13 - immediately after writing the files
0:01.13 - the second time after writing
0:44.34 - after an eject/re-insert
0:01.15 - the second time after the re-insert

These numbers reveal some interesting conclusions:

1: The UNIX file system driver is clearly not as optimized as the
others. 2 minutes to format a volume and 6:30 to write 500M is much
slower than the other three formats.

2: Mac OS Extended is more optimized for writing and formatting. It
easily has the fastest write-times.

3: Mac OS Extended apparently does not automatically put written-data
into the read-cache. So it has to actually read the volume when
reading back data that was written. The MS-DOS and UNIX drivers
appear to cache written-data, so the read-from-cache speed was
achieved on the first read test.

4: The read-from-media speeds (after eject/insert) are comparable for
all file systems. The differences are easily within experimental
error, given the fact that all kinds of stuff is running in the
background on this Mac.

5: The read-from-cache speeds (the "second time" read tests) for
non-journaled HFS are slower than journaled. This could simply be
experimental error, or it could be an issue with the driver (perhaps
journaling has a more aggressive caching system).

Given this, my recommendation for formatting flash would be:

- If you know you won't use the volume on a non-Mac system, format it
Mac OS Extended. This is clearly the fastest file system on Mac OS.

- If you're going to be using the volume on PCs, format it FAT32. It's
a bit slower when writing, but not all that bad overall.

- Don't bother with the UNIX file system unless you have a specific need
to use it.

-- David
.

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