[CentOS] RAID?

Mon Jun 25 23:33:15 UTC 2012
Dennis Jacobfeuerborn <dennisml at conversis.de>

On 06/26/2012 12:50 AM, Keith Keller wrote:
> On 2012-06-25, John R Pierce <pierce at hogranch.com> wrote:
>> On 06/25/12 1:10 PM, Alexander Dalloz wrote:
>>>> they really should be better integrated, like the way LVM and JFS are
>>>>> integrated on AIX.
>>>>>      # chfs -a size=+2G /var
>>>>> adds 2GB to /var, online, automatically.  grows the logical volume and
>>>>> resizes the file system, all at once.
>>> Don't know where software RAID comes into play on AIX, but what is the
>>> difference of that command above to this one on CentOS 6?
>>>        # lvresize -L+2G -r VG_sys/LV_var
>> does lvresize resize the file system while online? I didn't think it 
>> did.  the man page for fsadm (referenced in the lvresize man page) says 
>> ext2/3/4 is unmounted before resizing.   ooops.  kind of hard to umount 
>> /var !
> My man page for fsadm (CentOS 6) implies that you need to provide -e in
> order for fsadm to umount an ext? filesystem before attempting the
> resize.  So in theory if you don't give -e it should resize while
> mounted.

I know that a combination of lvextend and resize2fs can be done online. I
regulary add new virtual disks to guests and then add the space to the root
partition in these guests in fact I just added 100G of space to a mongodb
VM a few minutes ago.
While I haven't used the -r switch yet I would think that it uses the same
mechanism and thus should do all its work online as well.