All abot Hard Drive Formatting, Cylinder Size and Block Size

[Zac67]

Hmm - most flash media are probably optimized for ~4k block sizes (the Windoze default), but due to the flash file system sitting in between(!) the host addressable block structure and the physical blocks the actual block/cluster size may not really be the most important thing.

However, it's a smart move to not use the full capacity of a card but leave 10-20% empty. This ensures that the flash controller has ample blocks to choose from when storing new or changing existant data. In addition to being faster on writes this will also further reduce wear and tear of the flash cells. (The flash controller reserves some capacity of the actual chips anyway but adding to this reserve will help it do a better job.)

[Zac67]

Interesting.  You don't need them to match?

To optimize perfectly for a flash device you'd need to match both sizes. Drive geometry and partition positioning influence the position of the first partition sector which should be a multiple of the flash structure size (block) - it's probably smart to make a cylinder the size of the flash block, so all cylinders will be aligned.

The filesystem sector size influences the alignment of all following sectors. Too small a size will lead to excess rewriting of small sectors, too large a size will waste capacity and IDE bandwidth. You probably won't care about capacity nowadays, so 16 KB may be a good choice.

[Zac67]

I've heard it doesn't really matter what numbers you chose, as long as total number of sectors (heads*cylinders*sectors/track) is less or equal to real disk size.

With magnetic media it really doesn't; SCSI disks have never had a host observable geometry, neither have later IDE drives. However, flash memory can't really be written to in sector sizes = 512 bytes (the flash controller just makes you believe), and this is about optimizing for this factor.

[Zac67]

According to Wikipedia, common NAND flash block sizes are 16 to 512 KB, with larger, cheaper chips probably using larger blocks. 4 MB is probably well on the safe side, as is any larger power of 2.