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Recommended cluster size for FAT32 64GB SDXC card?

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Offline Razor512

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Recommended cluster size for FAT32 64GB SDXC card?
« on: 11 / May / 2014, 06:44:06 »
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I recently purchased a 64GB SDXC card, and used guiformat for format it as FAT32 so that CHDK would boot on my Powershot SX 230HS

The problem is that when in FAT32 mode, the 64K write speeds drop significantly VS the standard exfat

FAT32 benchmark


exfat



small cluster sizes such as 4096 will cause a very slow boot speed. Is there a recommended cluster size that will preserve as much write speed as possible?
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Offline lapser

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Re: Recommended cluster size for FAT32 64GB SDXC card?
« Reply #1 on: 12 / May / 2014, 17:34:26 »
I've been using 16,384 for 64GB SD cards with guiformat (the default is twice as large). I noticed problems with slow log file writes on the G1X while saving pictures with a 64GB card that didn't happen with the 32GB card. It seems to have helped.

16,384 is the default for the 32GB card with guiformat.

You might try formatting at different sizes and measuring boot speed and read/write speed to see what the difference is. That's what the "H" stands for. :)

Also, where did you find the benchmark program on the camera? Thanks.


« Last Edit: 12 / May / 2014, 17:39:02 by lapser »
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EOS-M3_120f / SX50_100b / SX260_101a / G1X_100g / D20_100b
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Offline Razor512

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Re: Recommended cluster size for FAT32 64GB SDXC card?
« Reply #2 on: 13 / May / 2014, 00:19:20 »
On the SX230 HS, it is located in the CHDK menu at

Miscellaneous stuff>  debug parameters >  benchmark

I will test the other sizes. (wish there was a way to make it auto boot from exfat, while it performs great with it, you have to manually do the firmware update step at each boot if you stick with exfat)
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Offline waterwingz

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Re: Recommended cluster size for FAT32 64GB SDXC card?
« Reply #3 on: 14 / May / 2014, 02:07:11 »
Quote from: Razor512 on 13 / May / 2014, 00:19:20
wish there was a way to make it auto boot from exfat, while it performs great with it, you have to manually do the firmware update step at each boot if you stick with exfat
Be happy that works at all.  Prior to 2011, Canon P&S cameras would only let CHDK boot from 4G or less FAT16 partitions.
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