What is sda1 used for?

I have two partitions: C: and D: (shown in Windows).

Then I installed Ubuntu and found out that /dev/sda represents a SCSI disk and a number after sda represents a partition.

Now, I assumed I have 2 partitions: /dev/sda and /dev/sda1 (one for C:, the other for D:), but this is not the case.

I have sda, sda1, sda2, sda3.

#fdisk -l

yields

Disk /dev/sda: 500.1 GB, 500107862016 bytes
255 heads, 63 sectors/track, 60801 cylinders, total 976773168 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: 0x3b7e273f Device Boot Start End Blocks Id System
/dev/sda1 * 2048 206847 102400 7 HPFS/NTFS/exFAT
/dev/sda2 206848 266242047 133017600 7 HPFS/NTFS/exFAT
/dev/sda3 266242048 976771071 355264512 7 HPFS/NTFS/exFAT

which explains all sda's except sda1.

What's happening on sda1? What is it used for?

1 Answer

Most likely this is a Windows 7 system reserved partition. This is needed to support BitLocker and Windows 7 created it even if you don't enable BitLocker so that you can enable it later.