Understanding output from fdisk

JockVSJock · 11-04-2014, 08:03 AM

Running RedHat Linux 5.8 x86_64 w/2.6 kernel.

I'm trying to make sense of the various partitions by the following commands:

Code:

[root@box1 etc]# fdisk -l | grep Disk
Disk /dev/sda: 72.9 GB, 72999763968 bytes
Disk /dev/sdb: 1073 MB, 1073741824 bytes
Disk /dev/sdc: 1073 MB, 1073741824 bytes
Disk /dev/sdd: 1073 MB, 1073741824 bytes
Disk /dev/sde: 1073 MB, 1073741824 bytes
Disk /dev/sdf: 1073 MB, 1073741824 bytes
Disk /dev/sdg: 1073 MB, 1073741824 bytes
Disk /dev/sdh: 284.8 GB, 284857860096 bytes
Disk /dev/sdi: 284.8 GB, 284857860096 bytes
Disk /dev/sdj: 284.8 GB, 284857860096 bytes
Disk /dev/sdk: 287.0 GB, 287005343744 bytes
Disk /dev/sdl: 287.0 GB, 287005343744 bytes
Disk /dev/sdm: 287.0 GB, 287005343744 bytes
Disk /dev/sdn: 287.0 GB, 287005343744 bytes
Disk /dev/sdo: 287.0 GB, 287005343744 bytes
Disk /dev/sdp: 287.0 GB, 287005343744 bytes
Disk /dev/sdq: 287.0 GB, 287005343744 bytes
Disk /dev/sdr: 287.0 GB, 287005343744 bytes
Disk /dev/sds: 549.7 GB, 549755813888 bytes
Disk /dev/sdt: 549.7 GB, 549755813888 bytes
Disk /dev/sdu: 1073 MB, 1073741824 bytes
Disk /dev/sdv: 1073 MB, 1073741824 bytes
Disk /dev/sdw: 1073 MB, 1073741824 bytes
Disk /dev/sdx: 1073 MB, 1073741824 bytes
Disk /dev/sdy: 1073 MB, 1073741824 bytes
Disk /dev/sdz: 1073 MB, 1073741824 bytes
Disk /dev/sdaa: 284.8 GB, 284857860096 bytes
Disk /dev/sdab: 284.8 GB, 284857860096 bytes
Disk /dev/sdac: 284.8 GB, 284857860096 bytes
Disk /dev/sdad: 287.0 GB, 287005343744 bytes
Disk /dev/sdae: 287.0 GB, 287005343744 bytes
Disk /dev/sdaf: 287.0 GB, 287005343744 bytes
Disk /dev/sdag: 287.0 GB, 287005343744 bytes
Disk /dev/sdah: 287.0 GB, 287005343744 bytes
Disk /dev/sdai: 287.0 GB, 287005343744 bytes
Disk /dev/sdaj: 287.0 GB, 287005343744 bytes
Disk /dev/sdak: 287.0 GB, 287005343744 bytes
Disk /dev/sdal: 549.7 GB, 549755813888 bytes
Disk /dev/sdam: 549.7 GB, 549755813888 bytes
Disk /dev/sdan: 1073 MB, 1073741824 bytes
Disk /dev/sdao: 1073 MB, 1073741824 bytes
Disk /dev/sdap: 1073 MB, 1073741824 bytes
Disk /dev/sdaq: 1073 MB, 1073741824 bytes
Disk /dev/sdar: 1073 MB, 1073741824 bytes
Disk /dev/sdas: 1073 MB, 1073741824 bytes
Disk /dev/sdat: 284.8 GB, 284857860096 bytes
Disk /dev/sdau: 284.8 GB, 284857860096 bytes
Disk /dev/sdav: 284.8 GB, 284857860096 bytes
Disk /dev/sdaw: 287.0 GB, 287005343744 bytes
Disk /dev/sdax: 287.0 GB, 287005343744 bytes
Disk /dev/sday: 287.0 GB, 287005343744 bytes
Disk /dev/sdaz: 287.0 GB, 287005343744 bytes
Disk /dev/sdba: 287.0 GB, 287005343744 bytes
Disk /dev/sdbb: 287.0 GB, 287005343744 bytes
Disk /dev/sdbc: 287.0 GB, 287005343744 bytes
Disk /dev/sdbd: 287.0 GB, 287005343744 bytes
Disk /dev/sdbe: 549.7 GB, 549755813888 bytes
Disk /dev/sdbf: 549.7 GB, 549755813888 bytes
Disk /dev/sdbg: 1073 MB, 1073741824 bytes
Disk /dev/sdbh: 1073 MB, 1073741824 bytes
Disk /dev/sdbi: 1073 MB, 1073741824 bytes
Disk /dev/sdbj: 1073 MB, 1073741824 bytes
Disk /dev/sdbk: 1073 MB, 1073741824 bytes
Disk /dev/sdbl: 1073 MB, 1073741824 bytes
Disk /dev/sdbm: 284.8 GB, 284857860096 bytes
Disk /dev/sdbn: 284.8 GB, 284857860096 bytes
Disk /dev/sdbo: 284.8 GB, 284857860096 bytes
Disk /dev/sdbp: 287.0 GB, 287005343744 bytes
Disk /dev/sdbq: 287.0 GB, 287005343744 bytes
Disk /dev/sdbr: 287.0 GB, 287005343744 bytes
Disk /dev/sdbs: 287.0 GB, 287005343744 bytes
Disk /dev/sdbt: 287.0 GB, 287005343744 bytes
Disk /dev/sdbu: 287.0 GB, 287005343744 bytes
Disk /dev/sdbv: 287.0 GB, 287005343744 bytes
Disk /dev/sdbw: 287.0 GB, 287005343744 bytes
Disk /dev/sdbx: 549.7 GB, 549755813888 bytes
Disk /dev/sdby: 549.7 GB, 549755813888 bytes
Disk /dev/emcpowern: 287.0 GB, 287005343744 bytes
Disk /dev/emcpowera: 1073 MB, 1073741824 bytes
Disk /dev/emcpowerd: 1073 MB, 1073741824 bytes
Disk /dev/emcpowerr: 549.7 GB, 549755813888 bytes
Disk /dev/emcpowers: 549.7 GB, 549755813888 bytes
Disk /dev/emcpowerq: 287.0 GB, 287005343744 bytes
Disk /dev/emcpowerm: 287.0 GB, 287005343744 bytes
Disk /dev/emcpowerc: 1073 MB, 1073741824 bytes
Disk /dev/emcpowerf: 1073 MB, 1073741824 bytes
Disk /dev/emcpowere: 1073 MB, 1073741824 bytes
Disk /dev/emcpowerb: 1073 MB, 1073741824 bytes
Disk /dev/emcpoweri: 284.8 GB, 284857860096 bytes
Disk /dev/emcpowerg: 284.8 GB, 284857860096 bytes
Disk /dev/emcpowero: 287.0 GB, 287005343744 bytes
Disk /dev/emcpowerh: 284.8 GB, 284857860096 bytes
Disk /dev/emcpowerl: 287.0 GB, 287005343744 bytes
Disk /dev/emcpowerj: 287.0 GB, 287005343744 bytes
Disk /dev/emcpowerp: 287.0 GB, 287005343744 bytes
Disk /dev/emcpowerk: 287.0 GB, 287005343744 bytes

I understand that /sda is the 1st partition and the s is scsi emulation. I'm just not sure why there are so many different partitions.

Also I believe this is on a phyiscal Blade server with two 72 GB Disk Drives, however I only see one (the physical Blade has a RAID 1 config, according to what notes I can find on this).

This is on some sort of SAN because of the last /dev/emcpower#, which is software for EMC Power Path.

thanks

smallpond · 11-04-2014, 08:17 AM

Most likely sda is your RAID 1 of two physical disks. Only the resulting logical disk is visible to the kernel so it looks like a single disk.

sdb - sdby are individual paths to your EMC SAN, they are not all separate disks. Run the powerpath software to see how much unique storage is attached.

Note on terminology: Disks refer to whole volumes, either physical or logical, and have a name ending in a letter like sda. A partition is a portion of a disk, and would have a name like /dev/sda1 or /dev/sda2, etc.