linux box HDD size question

[Nigel Wade]

M E Fieu wrote:
> Hi.. May I know how to check a size of the HDD (s) in a linux box. If I issued the following
> command, does it mean the total HDD size is 30G ??  

No, it only shows the filesystems which are mounted.

> Could it be some of the HDD space is not used
> ??  

Yes, there may be unused space on the disk (not allocated to any 
partition/filesystem) and filesystems which are not mounted. They would not be 
shown by df.

> If yes, how to check the real disk space??  Besides, how do we check what is the RAID type and
> how many HDD is beside the box via linux command or other mean ?

See below.

> 
> [root at linux root]# df -h
> Filesystem            Size  Used Avail Use% Mounted on
> /dev/sda3             4.0G  289M  3.5G   8% /
> /dev/sda9             6.6G  1.9G  4.5G  30% /apps
> /dev/sda1             250M   45M  193M  19% /boot
> /dev/sda6             5.0G  1.7G  3.1G  36% /home
> none                  1.3G     0  1.3G   0% /dev/shm
> /dev/sda8             2.0G   83M  1.8G   5% /tmp
> /dev/sda7             4.0G  3.1G  712M  82% /usr
> /dev/sda5             6.9G  157M  6.4G   3% /var
> 
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fdisk -l will list information on all the hard drives it finds. This includes 
the size, and the partition information.

 From the partition information you can tell if there are any RAID partitions, 
they have type fd and are listed as "Linux raid autodetect".

e.g.

# fdisk -l

Disk /dev/sda: 73.5 GB, 73543163904 bytes
255 heads, 63 sectors/track, 8941 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

    Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1          10       80293+  fd  Linux raid autodetect
/dev/sda2              11        1035     8233312+  82  Linux swap
/dev/sda3            1036        3646    20972857+  fd  Linux raid autodetect
/dev/sda4            3647        8941    42532087+   5  Extended
/dev/sda5            3647        4951    10482381   fd  Linux raid autodetect
/dev/sda6            4952        5604     5245191   fd  Linux raid autodetect
/dev/sda7            5605        8941    26804421   fd  Linux raid autodetect

Disk /dev/sdb: 73.5 GB, 73543163904 bytes
255 heads, 63 sectors/track, 8941 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

    Device Boot      Start         End      Blocks   Id  System
/dev/sdb1   *           1          10       80293+  fd  Linux raid autodetect
/dev/sdb2              11        1035     8233312+  82  Linux swap
/dev/sdb3            1036        3646    20972857+  fd  Linux raid autodetect
/dev/sdb4            3647        8941    42532087+   5  Extended
/dev/sdb5            3647        4951    10482381   fd  Linux raid autodetect
/dev/sdb6            4952        5604     5245191   fd  Linux raid autodetect
/dev/sdb7            5605        8941    26804421   fd  Linux raid autodetect

Disk /dev/sdc: 1229.3 GB, 1229375668224 bytes
255 heads, 63 sectors/track, 149463 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

    Device Boot      Start         End      Blocks   Id  System
/dev/sdc1               1      100000   803249968+  83  Linux
/dev/sdc2          100001      149463   397311547+  83  Linux

This shows some of the disks on our server. The first 2 are the mirrored system 
disks, which contain the swap areas and RAID partitions. /dev/sdc is a 1.2TB 
external RAID box which is divided into 2 partitions.

-- 
Nigel Wade, System Administrator, Space Plasma Physics Group,
             University of Leicester, Leicester, LE1 7RH, UK
E-mail :    nmw at ion.le.ac.uk
Phone :     +44 (0)116 2523548, Fax : +44 (0)116 2523555