[NTLUG:Discuss] Software RAID using file "device"?

[Stuart Johnston]

Drew Myers wrote:
> * Stuart Johnston (saj at thecommune.net) wrote:
> 
>>I have a server with two partitions, / and /home (not the best 
>>setup, I know).  The /home partition is coming very close to 
>>running out of disk space and I am trying to figure out a way to 
>>use some of the extra space on / without requiring a trip down to 
>>the data center.  This would only need to be a temporary solution.
>>
>>When I setup the system, I didn't worry too much about the 
>>partition setup because I was using LVM, which I thought would 
>>allow me to easily re-allocate the partitions as needed.  It turns 
>>out not to be quite so easy since you can't generally resize an 
>>ext3 partition while it is mounted.
>>
>>I was thinking about how in Linux, devices are treated like files 
>>and you can often use them interchangeably.  So, if I created a 
>>file on / then I could use it as a device in mdadm or lvm to 
>>combine linearly with the /home partition (which can be unmounted 
>>and resized remotely). Unfortuntately, neither mdadm nor lvm seem 
>>to be willing to work with a non-block device.
>>
>>Any suggestions on how to make this work?
> 
> 
> What OS are you running?  In RHEL4 you can use the ext2online utility to
> resize the FS while it's mounted.

ext2online will only expand, not shrink a mounted fs.  Thanks for the 
suggestion though.  I didn't know RHEL4 (which this server is in fact 
running) had that kernel patch.

Thanks,
Stuart