Extending a raid 5

JJX · 04-14-2008, 01:11 PM

hi,

i have a Smart Array 5i/532 controller. I have configured a raid 5 with 3 hard disks. After some time i added two more hard disks. Using HP ACU i extended the array to include the new two hard disks (total 5). It seems that the array was rebuild successfully.

However, after the process finished, i was expecting linux to show some new space at the end of the raid (fdisk -l). But noting new appears.

Do i have to do any additional actions?

Thanks

blacky_5251 · 04-14-2008, 10:37 PM

It sounds like you have a hardware RAID controller, which makes the individual disks "invisible" to the operating system. The hardware controller simply presents a single device to the Op/Sys which the OpSys can use to create file systems on. The Op/Sys is unaware that the disk is a pseudo device controlled by the RAID controller or how many disks are used by the array.

What you've done is only half of the full process to utilize the extra disk space. If you run fdisk on the raid device, you will probably see that your exiting partition isn't taking up all of the available space on the disk.

How you proceed next depends on whether you are using logical volumes (LVM) of not, but the ultimate aim is to resize your filesystem so it uses the additional space now available on the raid device.

I recommend you do some research on either, LVM and increasing LVM filesystems, or increasing partion and file-system sizes. You may need to use a Live-CD to boot from if you are resizing Op/Sys critical file-systems (e.g. / or /usr).

JJX · 04-15-2008, 02:04 AM

fdisk isnt finding the additional unallocated space.

I am not using LVM and as far as i know i cant install/implement it after the partitions are created. I dont want to resize the current parition scheme but only create a new partition using the unallocated space.

Do i have to install any additional utilites to find that space?

blacky_5251 · 04-15-2008, 04:56 AM

Can you post the output from "fdisk -l"?

JJX · 04-15-2008, 12:37 PM

Quote:

Originally Posted by blacky_5251

Can you post the output from "fdisk -l"?

Code:

myserver#fdisk -l

Disk /dev/cciss/c0d0: 145.6 GB, 145659002880 bytes
255 heads, 63 sectors/track, 17708 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x000bb091

           Device Boot      Start         End      Blocks   Id  System
/dev/cciss/c0d0p1               1         122      979933+  83  Linux
/dev/cciss/c0d0p2             123        4377    34178287+  83  Linux
/dev/cciss/c0d0p3            4378        5593     9767520   83  Linux
/dev/cciss/c0d0p4            5594        8854    26193982+   5  Extended
/dev/cciss/c0d0p5            5594        8122    20314161   83  Linux
/dev/cciss/c0d0p6            8123        8608     3903763+  83  Linux
/dev/cciss/c0d0p7            8609        8854     1975963+  82  Linux swap / Solaris

145.6 is the space (plus the new disks)
No new unallocated space appears

blacky_5251 · 04-15-2008, 05:39 PM

Yes it has, you're just not looking in the right place for it

The last partition on the "disk" array finished at 8854. The disk has cylinders up to 17708. So all that space from 8855 up to 17708 is unallocated and unused.

Code:

myserver#fdisk -l

Disk /dev/cciss/c0d0: 145.6 GB, 145659002880 bytes
255 heads, 63 sectors/track, 17708 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x000bb091

           Device Boot      Start         End      Blocks   Id  System
/dev/cciss/c0d0p1               1         122      979933+  83  Linux
/dev/cciss/c0d0p2             123        4377    34178287+  83  Linux
/dev/cciss/c0d0p3            4378        5593     9767520   83  Linux
/dev/cciss/c0d0p4            5594        8854    26193982+   5  Extended
/dev/cciss/c0d0p5            5594        8122    20314161   83  Linux
/dev/cciss/c0d0p6            8123        8608     3903763+  83  Linux
/dev/cciss/c0d0p7            8609        8854     1975963+  82  Linux swap / Solaris

I suggest you modify the extended partition to finish at 17708, and then you can start to make use of it by adding or resizing extended partitions.

How you proceed from here depends on you. It is easy to use the space for new filesystems by creating new partitions with fdisk and then new partitions with mke2fs, but resizing existing filesystems and partitions is trickier, and like I suggested, might be best done using a LiveCD.