I've got a flash drive and I want to understand the properties of it as is outputted from fdisk
. I inserted it and check the dmesg
and I could see that it was mounted as /dev/sdb1
so I ran fdisk
to see what is reported for /dev/sdb
mike@mike-Qosmio-X770:~$ sudo fdisk -l
[sudo] password for mike:
Disk /dev/sdb: 127 MB, 127926272 bytes
16 heads, 32 sectors/track, 488 cylinders, total 249856 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x6b3ee723
Device Boot Start End Blocks Id System
/dev/sdb1 * 32 249854 124911+ b W95 FAT32
As far as I can tell, the drive is a 128MB FAT32 formatted flash drive, it only has 1 partition on it. It starts at "32" (presumably 0-31 is used for some FTL).
It's reporting a "sector" is 512 bytes in size and there are 249,856 sectors (122MB total).
Now I'm confused about the Cylinder, head, and sectors/track count. I know cylinders/heads have to do with Magnetic disk storage types. Is there any meaning for these when it comes to a flash device? Or is this just "left over" information from fdisk
which really has no meaning to a non-magnetic storage medium? If the later, why give values at all?
Second question, what is the "size" of a block? :
Blocks
124911+
And what is the meaning of the +
after the block count?
Best Answer
Size of a Block
Source: Partitioning with fdisk
Source: Linux disk block size... help please
Sectors 0-31
To answer your question about the first 32 sectors, as the flash drive is a FAT formatted device then looking at the FAT file system definition, one can see that a FAT file system is composed of four different sections:
a) The Reserved Sectors;
b) The File Allocation Table (FAT) region;
c) The Root Directory Region, and;
d) The Data Region.
Just additional information, not relevant to the OP question
Source: Wikipedia - File Allocation Table