topic Re: raid 5 in Operating System - Linux

raid 5

John Straq — Mon, 09 Mar 2009 11:10:07 GMT

Can someone help me?
HP DL 380 G4 raid 5 3 Hard disks
is one logical drive.
after adding one drive to array it is showing unused space the size off that added drive.
Why is it unused space and why is it not added to the logical drive.
when I want to use it do I have to make a new logical drive now?
I prefer to see the original logical drive becomes bigger wthout losing the data.

Re: raid 5

Alexander Chuzhoy — Mon, 09 Mar 2009 11:30:29 GMT

Assuming you run the latest RedHat release.
first you have to run pvcreate , where the represents the newly installed hard drive.
Then you need to extend the volume group.
vgextend VolumeGroupName , again where the represents the newly installed hard drive.
Then you could extend the logical volume (lvextend) and finally grow the file system with resize2fs.

Re: raid 5

Uwe Zessin — Mon, 09 Mar 2009 12:08:02 GMT

The logical disk's size is not automatically increased, because:

- not all operating systems deal well with an increased logical disk size

- and some people indeed may want to create an additional logical disk instead of growing the/an existing one

Re: raid 5

John Straq — Mon, 09 Mar 2009 12:31:48 GMT

Is this also working for Suse enterprise Server 9 using
ReiserFS and two partitions on it
I want to extend one off them with the new drive space.
There is already data on this server.

Re: raid 5

Steven E. Protter — Mon, 09 Mar 2009 13:27:19 GMT

Shalom,

Don't forget to provide Red Hat a non-raid 5 area from which to boot. It won't boot from a raid 5 array.

From experience, you will need to create a new logical drive. Expansion would require a full system backup and restore.

SEP

Re: raid 5

Ciro Iriarte — Mon, 09 Mar 2009 13:35:26 GMT

What's the output of:

hpacucli ctrl slot=0 show status
hpacucli ctrl slot=0 ld all show status
hpacucli ctrl slot=0 pd all show status

Re: raid 5

Uwe Zessin — Mon, 09 Mar 2009 16:49:38 GMT

> It won't boot from a raid 5 array.

I am very sure John is working with a hardware RAID-5 which is presented as a single disk to the OS.

Re: raid 5

Robert Walker_8 — Mon, 09 Mar 2009 23:10:00 GMT

Gday,

If you have added a drive to an existing array that wont be available (shown up as unused space) until you expand the array. This doesnt generally cause problems but a backup is advised - the expansion process is transparent to the OS except some performance degradation. See smartarray controller settings about expansion (as low, medium, high).

After the expansion, you can then create a new lun. If you use LVM on the server then you can create the new lun and add to the existing pv pool and then expand lv lun as required.

Robert.

Re: raid 5

John Straq — Thu, 12 Mar 2009 12:51:32 GMT

Oke guys this is the situation.
I booted in the past and still do from this array.
Add a drive and extended the array succesfully.
In the OS suse enterprise server 9 via Yast I can see that there is this space more or less the size off the new added drive that I should be able to add to the partition /usr.
In Yast there is a button with 'adjust size' on it so I highlite the \usr partition and add the free space and press the button 'adjust size'.
the result is ...unable to resize \usr
any ideas?

Re: raid 5

Ciro Iriarte — Thu, 12 Mar 2009 13:35:42 GMT

Are you using LVM?, the easiest way would be to create a new partition, define it as a PV and add it to the VG.

If you're not using LVM, probably can't resize partitions (depends on the actual layout) and if your layout helps, it must be done offline.

Re: raid 5

John Straq — Thu, 12 Mar 2009 14:49:23 GMT

No I am not useing lvm and if it is possible I prefer to extend it not useing it.
If there is no other way then to use lvm it does probebly effect the application and have to install / configure it
I find it strange that in YAST there is this button and as far as I can see should this extending be possible
swap starts on 1 and ends on 301
\ starts on 302 and ends on 9001
\usr starts on 9002 and ends on 105529200
does'nt this show that the extention of \usr should be possible? or has the array something to do with it

Re: raid 5

Ciro Iriarte — Thu, 12 Mar 2009 17:32:22 GMT

Well, given you are not using LVM already, it's a dead end...

On the other side, you can resize the partition holding /usr as it's the last of the disk, but it only can be done offline (the filesystem can't be mounted.)

Doing it by hand (assuming you won't have yast partitioner available booting from rescue DVD), implies deleting it and recreating a bigger one in its place.

At last, resizing a reiser fs can be done online once you recreate the partition.

Re: raid 5

Robert Walker_8 — Sun, 15 Mar 2009 23:46:19 GMT

Gday,

If your not using LVM, then the best is use dump to somewhere else

dump -0 -j6 -f /tmp/var.dmp.Z /var

Or whatever file system is that you need to do!

If the old file system is small then maybe you can sacrifice it? Another option is start using LVM on the newer area and bring the rest of the system up through it?

Steps to LVM are pretty easy - by default LVM should be installed - a simple check should determine if its there?

1. fdisk new device to #8e (although this doesnt always need doing?)
2. pvcreate /dev/device (on HP /dev/cciss/c0d1)
2a. pvs to check or pvdisplay
3. vgcreate VG0 /dev/cciss/c0d1
VG0 is volume name - arbitrary name but used in mount unless using devmapper - this is similar to a LUN and in the sense and you can have multiple "partitions" from a volume group and multiple volume groups.
3a. vgs or vgdisplay
4. lvcreate -n LV01 -L 20G /dev/VG0
this creates a LVM LUN called LV01 of 20G from the volume group VG0. This is then formated and mounted - late you can resize depending upon file system. EXT3 resize2fs but has to be off line.

Still if this cant be done then you can with some pain and anguish dump all files systems to tape or network using single user mode or (probably on SUSE) use the OS recovery disk - RHEL allows the system to boot to emergency and can be done there. Have done this and others have probably been there as well it aint the most fun!

Robert.

Re: raid 5

Taifur — Mon, 16 Mar 2009 03:51:16 GMT

Hi John,

After creating RAID 5 from ORCU (option Rom Configuration Utility)with 3 harddisk it will show 1 logical drive. But if you add additional one harddisk it will show unused space because it is not included with this RAID5 configuration.The information during RAID5 configuration will be exist in array rom. So, for adding additional disks you have to create RAID again .

rgds//
Taifur

Re: raid 5

John Straq — Tue, 17 Mar 2009 13:26:44 GMT

Oke guys I managed it with your help.
Thank you!