[CentOS] Growing RAID5 on CentOS 4.6

Ross S. W. Walker RWalker at medallion.com
Fri Aug 22 19:31:31 UTC 2008


Stephen Harris wrote:
> On Fri, Aug 22, 2008 at 03:05:30PM -0400, Ross S. W. Walker wrote:
> > Stephen Harris wrote:
> 
> > Or you could just boot from a LiveCD of a distro that was this and
> > run a conversion there, it would make it unavailable during the
> > conversion though.
> 
> *grin*  My first email on this subject...
>   
>   I wonder if I could boot off a Ubuntu CD or something and grow the array
>   that way.  Would be annoying (many hours of server downtime)...

I wouldn't use Ubuntu or any Debian based distro cause it's EVMS just
might bugger up the LVM config...

Try Fedora or OpenSuse they use straight LVM.

> > If the array was part of a LVM VG, you could create another 4 drive
> > array and add it to the VG and extend the LVs that way, or do a
> > pvmove and move everything from the old array to the new.
> 
> Well, it _is_...  the old array was 4*500Gb.  The new array is 5*1Tb.
> In each I've built a single VG/LV.  But my machine can't handle 9 SATA
> disks (power, controller limitations, space).  So what I did was use one
> of the TByte disks to copy the data, built the other 4 into an array,
> copied the data from the last disk onto the array and then... failed to
> extend the array.
> 
> I still have the old 4*500GB on a shelf, but I don't have anything I can
> plug it into.
> 
> (My other option is to buy a couple of SATA controllers, build a second
> machine then transfer data over the network)

Instead of a second machine, how about an external disk enclosure?

You can get them rack mountable or tower based. Look for a nice
15 drive enclosure, then you have room to build 2 arrays...

A nice hardware RAID card with battery backed cache would make
the arrays scream too, for RAID5/6 I always go hardware with
BBU Cache. I almost always do the OS disks as software RAID1.

Hey with the enclosure going you can use the internal drives
for volume snapshots and be able to keep quite a few without
killing the storage performance.


-Ross

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