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The USB in question is Sandisk Ultra Fit 128GB.
It'll be formatted as exFAT. Allocation units options range from 4k to 32M

What would be the best allocation units size if I were to use it to store exclusively ISOs? More specifically OS ISOs to be used with Ventoy. This would mostly include linux distros

Do ISO behave as one large file, or a folder containing independent files? Same with other files like zip and rar.

SparkShredder
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  • See https://superuser.com/questions/465615/downsides-of-a-small-allocation-unit-size/465638#465638 and https://superuser.com/questions/1520373/using-a-2048-kilobytes-allocation-unit-size-for-large-files/1520400#1520400 – sawdust Aug 02 '22 at 18:52

1 Answers1

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Ventoy works with ISO files, where each ISO is just one single file.

The allocation unit size is not really important, as the files would in most cases be read in a sequential manner, where most files within the ISO would be much larger than the allocation unit.

You may accept the default allocation size that is offered by the formatting utility.

harrymc
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  • i believe it's 128K. Isn't that bit too much though? I was thinking of going with 16k/32k. – SparkShredder Aug 02 '22 at 10:35
  • Most files within the ISO would have sizes measured in megabytes or at least hundreds of K. A large sector size would actually reduce the number of read operations. As the ISO files are very large, the lose on their last partially-filled sector is insignificant, no matter the sector size. – harrymc Aug 02 '22 at 10:51
  • FWIW I'd be fairly surprised if you see any significant gain from upping the cluster (allocation unit) size. It was quite some time ago I played with these, but even then the gain was limited. Possibly there might be some gain from upping the size for larger files. This was before FAT32 though, so might be moot today. – Hannu Aug 02 '22 at 17:01
  • This might be interesting to read -> https://en.wikipedia.org/wiki/Design_of_the_FAT_file_system#Cluster_map – Hannu Aug 02 '22 at 17:06