On 20/09/2020 14.40, Anton Aylward wrote:
On 19/09/2020 13:25, Carlos E. R. wrote:
It is 7.558GB, or 7GiB. No way 8GB.
So fdisk says 14761984 sectors So f3 says 14731112 sectors
A 39872 sector difference.
f3 looks at the partition. fdisk looks at the entire device. The full output was: Telcontar:/data/storage_b # fdisk -l /dev/sde Disk /dev/sde: 7 GiB, 7558135808 bytes, 14761984 sectors Disk model: Transcend 8GB Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disklabel type: dos Disk identifier: 0xa952c083 Device Boot Start End Sectors Size Id Type /dev/sde1 2048 14761983 14759936 7G b W95 FAT32 Telcontar:/data/storage_b # Thus, 14759936 the partition. Somewhat less writeable space. I could look at "df", but the stick now contains the 5.2 ISO. I can try with another stick, uonopened. Ok, it has: Telcontar:~ # fdisk -l /dev/sde Disk /dev/sde: 7 GiB, 7558135808 bytes, 14761984 sectors Disk model: Transcend 8GB Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disklabel type: dos Disk identifier: 0xc3072e18 Device Boot Start End Sectors Size Id Type /dev/sde1 56 14761983 14761928 7G b W95 FAT32 Telcontar:~ # The number of sectors vary, but this is the original formatting by the manufacturer, while the previous stick was done by gparted. Telcontar:~ # df /media/Transcend/ Filesystem 1K-blocks Used Available Use% Mounted on /dev/sde1 7364580 4 7364576 1% /media/Transcend Telcontar:~ # Multiplying by two - or: Telcontar:~ # df --block-size=512 /media/Transcend/ Filesystem 512B-blocks Used Available Use% Mounted on /dev/sde1 14729160 8 14729152 1% /media/Transcend Telcontar:~ # f3 said 14731112, this is similar. I could reformat with parted and see. [...] Done: Telcontar:~ # fdisk -l /dev/sde Disk /dev/sde: 7 GiB, 7558135808 bytes, 14761984 sectors Disk model: Transcend 8GB Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disklabel type: dos Disk identifier: 0x7d890169 Device Boot Start End Sectors Size Id Type /dev/sde1 2048 14761983 14759936 7G b W95 FAT32 Telcontar:~ # Telcontar:~ # df --block-size=512 /media/BORRAME/ Filesystem 512B-blocks Used Available Use% Mounted on /dev/sde1 14731120 8 14731112 1% /media/BORRAME Telcontar:~ # Which is the same figure as F3 gives. QED :-D
If I was asked to speculate on the 'why' I'd first suggest that the 'shortfall' are what might be termed "error correction lookaside sectors" and the metadata to make it work.
Back in the days when rotating rust took two men to life, I implemented a error correction system, the likes of which I'm sure is built into modern drives transparently. It revered a few cylinders that substituted for one gone bad. The driver had a look-aside table. A seek for the bad cylinder was redirected to the lookaside. Yes it slowed things down, yes it gave up some disk capacity. Yes you had to make a best effort to copy the stuff from the sector-gone-bad to the lookaside.
I'm sure its a lot more sophisticated now. I'm sure its built into the firmware of the device.
That would be my first guess.
A second guess isn't going to happen until after a second pot of coffee and isn't going to happen on a Sunday.
:-) -- Cheers / Saludos, Carlos E. R. (from 15.1 x86_64 at Telcontar)