Linux: Listing all local and SAN disks on a host

linuxstorage

I am attempting to list and categorize all connected disks on a host; local and SAN-connected. The SAN use various types of adapters (namely Emulex and Qlogic) so scanning the FC bus can be somewhat unreliable (some hosts use both types for whatever reason). Basically I am gathering data for various reporting and analytics.

My question is this: if I use 'blkid' to list local disks, and 'lsscsi' to list the SAN devices attached via fibrechannel, will that encompass all of the disks connected to the host?

I've not had a lot of experience with either command to know the in's and out's of them, so I wanted to see if their results are reliable enough to build a data framework.

I should note that this is a heavily scrutinized environment and extraneous tools will not be permitted to be installed.

Best Answer

I'd probably just compare fdisk -l and lsscsi.

On my systems, I tend to see more output in fdisk, as lsscsi doesn't account for all of the block devices in use on the servers (ZFS zpool devices, etc.) Similar situation for blkid.

Related Solutions

The difference between SAN, NAS and DAS

First it is best to define the difference between a block device and filesystem. This is easier grasped if you are familiar with UNIX because it makes an objective distinction between the two things. Still the same applies to Windows.

A block device is a handle to the raw disk.
- Such as /dev/sda for a disk or /dev/sda1 for a partition on that disk.
A filesystem is layered on top of the block device in order to store data. You can then mount this.
- Such as mount /dev/sda1 /mnt/somepath.

With those terms in mind it's then easier to see the distinction between the following.

DAS is a block device from a disk which is physically [directly] attached to the host machine.
- You must place a filesystem upon it before it can be used.
- Technologies to do this include IDE, SCSI, SATA, etc.
SAN is a block device which is delivered over the network.
- Like DAS you must still place a filesystem upon it before it can used.
- Technologies to do this include FibreChannel, iSCSI, FoE, etc.
NAS is a filesystem delivered over the network.
- It is ready to mount and use.
- Technologies to do this include NFS, CIFS, AFS, etc.

Linux RHEL how to differentiate between a local disk and a SAN disk

There's a couple different approaches you can take. Some may be better or worse for your particular setup. Remember, strictly speaking a Fibre Channel drives does not necessarily mean "SAN" or "Storage Array". It may just be an actual FC-attached drive.

You can check to see which SCSI host the drive is on and filter that way if you know, for example, that all your servers have (i.e) QLogic cards:

# lsscsi -H; lsscsi -g
[0]    qla2xxx       
[1]    qla2xxx       
[2]    mptsas        
[3]    ata_piix      
[4]    ata_piix      
[0:0:0:0]    disk    IBM      1814      FAStT  0916  /dev/sda  /dev/sg0
[0:0:0:1]    disk    IBM      1814      FAStT  0916  /dev/sdb  /dev/sg1
[0:0:0:2]    disk    IBM      1814      FAStT  0916  /dev/sdd  /dev/sg3
[0:0:0:31]   disk    IBM      Universal Xport  0916  -         /dev/sg4
[1:0:0:0]    disk    IBM      1814      FAStT  0916  /dev/sdc  /dev/sg2
[1:0:0:1]    disk    IBM      1814      FAStT  0916  /dev/sde  /dev/sg5
[1:0:0:2]    disk    IBM      1814      FAStT  0916  /dev/sdf  /dev/sg6
[1:0:0:31]   disk    IBM      Universal Xport  0916  -         /dev/sg7

Check the di VPD page for the device in question to see what protocol it's using.

# sg_vpd -p di /dev/sda
Device Identification VPD page:
  Addressed logical unit:
    designator type: NAA,  code_set: Binary
      0x600a0b80002664e2000026c349dda1ee
  Target port:
    designator type: NAA,  code_set: Binary
     transport: Fibre Channel (FCP-2)
      0x200600a0b8266f7f
    designator type: Relative target port,  code_set: Binary
     transport: Fibre Channel (FCP-2)
      Relative target port: 0x1
  Target device that contains addressed lu:
    designator type: NAA,  code_set: Binary
     transport: Fibre Channel (FCP-2)
      0x200600a0b8266f7e

Check using the path management tools for your particular storage array to see if the device is on that array. For example:

# sg_rdac /dev/sda
RDAC Legacy page
  Controller serial: 1T63717016
  Alternate controller serial: 1T64109650
  RDAC mode (redundant processor): alternate controller present; Dual active mode
  RDAC mode (alternate processor): alternate controller present; Dual active mode
  Quiescence timeout: 75
  RDAC option 0x6
  LUN Table:
    0: a a x x x x x x
    1: x x x x x x x x
    2: x x x x x x x x
    3: x x x x x x x x

versus:

# sg_rdac /dev/sda
invalid field in cdb (perhaps subpages or page control (PC) not supported)

Best Answer

Related Solutions

The difference between SAN, NAS and DAS

Linux RHEL how to differentiate between a local disk and a SAN disk

Related Topic