extending raid-5 ?

extending raid-5 ?

[Rainer Fuegenstein]

hi,

I'm currently using a 4*750GB SATA RAID-5 under centos 5.2 (mdadm
v2.6.4, kernel 2.6.18-128.1.6.el5) which I need to exend by replacing
the 750GB disks with 1.5TB ones.

since the mainboard has only 4 SATA ports, I need to replace one disk
after the other. I came up with the following plan:

1) fail first disk
  mdadm /dev/md0 -f /dev/sda1

2) remove first disk
  mdadm /dev/md0 -r /dev/sda1

3) shutdown the server, unplug 750GB sda drive, plug in 1.5TB drive

4) create a linux raid autodetect partition on sda which covers the
whole 1.5TB

5) add new device to the raid5 and wait until resync has finished
  mdadm /dev/md0 -a /dev/sda1
  
... repeat steps 1 tp 5 for sdb to sdd

6) grow the raid
  mdadm --grow /dev/md0

7) resize the xfs filesystem
   xfs_growfs /md0-mount-point
   
is this the proper way to do it, are there any issues I should know
about ?

thnx in advance.

Re: extending raid-5 ?

[Redeeman]

On Mon, 2009-05-11 at 01:00 +0200, Rainer Fuegenstein wrote:
> hi,
> 
> I'm currently using a 4*750GB SATA RAID-5 under centos 5.2 (mdadm
> v2.6.4, kernel 2.6.18-128.1.6.el5) which I need to exend by replacing
> the 750GB disks with 1.5TB ones.
> 
> since the mainboard has only 4 SATA ports, I need to replace one disk
> after the other. I came up with the following plan:
> 
> 1) fail first disk
>   mdadm /dev/md0 -f /dev/sda1
> 
> 2) remove first disk
>   mdadm /dev/md0 -r /dev/sda1
> 
> 3) shutdown the server, unplug 750GB sda drive, plug in 1.5TB drive

If you are going to do downtime anyway, i would suggest you just down
the box, and then copy the data with dd, that way you should probably be
able to avoid the costly resync, plus temporary loss of redundancy

> 4) create a linux raid autodetect partition on sda which covers the
> whole 1.5TB
> 
> 5) add new device to the raid5 and wait until resync has finished
>   mdadm /dev/md0 -a /dev/sda1
>   
> ... repeat steps 1 tp 5 for sdb to sdd
> 
> 6) grow the raid
>   mdadm --grow /dev/md0
> 
> 7) resize the xfs filesystem
>    xfs_growfs /md0-mount-point
>    
> is this the proper way to do it, are there any issues I should know
> about ?

> 
> thnx in advance.
> 
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Re: extending raid-5 ?

[Jeff Rippy]

But don't copy the partition map at the beginning of the drive
otherwise you'll end up with 1.5tb drives that have a 750gb partition.
 Someone confirm but I believe that's the first 512 bytes when copying
with dd.

Jeff

On Mon, May 11, 2009 at 12:11 AM, Redeeman <redeeman@metanurb.dk> wrote:
>
> On Mon, 2009-05-11 at 01:00 +0200, Rainer Fuegenstein wrote:
> > hi,
> >
> > I'm currently using a 4*750GB SATA RAID-5 under centos 5.2 (mdadm
> > v2.6.4, kernel 2.6.18-128.1.6.el5) which I need to exend by replacing
> > the 750GB disks with 1.5TB ones.
> >
> > since the mainboard has only 4 SATA ports, I need to replace one disk
> > after the other. I came up with the following plan:
> >
> > 1) fail first disk
> >   mdadm /dev/md0 -f /dev/sda1
> >
> > 2) remove first disk
> >   mdadm /dev/md0 -r /dev/sda1
> >
> > 3) shutdown the server, unplug 750GB sda drive, plug in 1.5TB drive
>
> If you are going to do downtime anyway, i would suggest you just down
> the box, and then copy the data with dd, that way you should probably be
> able to avoid the costly resync, plus temporary loss of redundancy
>
> > 4) create a linux raid autodetect partition on sda which covers the
> > whole 1.5TB
> >
> > 5) add new device to the raid5 and wait until resync has finished
> >   mdadm /dev/md0 -a /dev/sda1
> >
> > ... repeat steps 1 tp 5 for sdb to sdd
> >
> > 6) grow the raid
> >   mdadm --grow /dev/md0
> >
> > 7) resize the xfs filesystem
> >    xfs_growfs /md0-mount-point
> >
> > is this the proper way to do it, are there any issues I should know
> > about ?
>
> >
> > thnx in advance.
> >
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-raid" in
> > the body of a message to majordomo@vger.kernel.org
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
>
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