growfs, old disks, gvinum - filesystem expansion and corruption

[Eric Anderson]

On 08/01/06 15:08, Lee Damon wrote:
> I have several FreeBSD-6.1 based file servers.  Each one has a hardware 
> RAID-based system that presents a single large (800G to 2TB) "disk" to 
> the OS.
> 
> In looking around for a FBSD-supported method of slicing this disk up 
> into usable (and later growable) file systems the only thing I found was 
> gvinum.  The other geom commands don't seem to deal with the idea of 
> slicing off parts of a large drive.
> 
> In a process very similar to the LVM commands I've used on other systems 
> I set up the boxes, calved off some disk as gvinum "drives", formatted 
> with newfs -U /dev/gvinum/..., added data and served forth.  Then as 
> file systems filled up I expanded those file systems.  When the data was 
> no longer needed (testing was done, it was time to go production) I 
> removed those file systems by unmounting them and using rm in the gvinum 
> command. I then created new file systems and the time has recently come 
> to expand them.
> 
> Now I discover that gvinum + growfs = Bad Things<tm>.  It seems that 
> when a file system is grown over "old file systems" (that supposedly no 
> longer exist) and then fsck is run it finds those old file systems and 
> shoves random stuff (including device nodes in some cases) into the 
> lost+found directory on the current file system. fsck(8) gives many 
> complaints about "unexpected soft update inconsistency", unref dir", 
> bad/dup file", and "allocated frags marked free" & "allocated files 
> marked free".  The rub being when I try to remove the old cruft from 
> lost+found I run a good probability of triggering a kernel panic.
> 
> My questions are:
> 1. Is there any way to clean up the old file system cruft without 
> crashing/trashing/deleting the system?

You could use dd to write zeros over the old areas to wipe out the old 
filesystem data.  Careful!

> 2. What tool should I be using to calve off slices of a 'huge' drive and 
> later expand it?

Why not use fdisk/bsdlabel?

Eric



-- 
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Eric Anderson        Sr. Systems Administrator        Centaur Technology
Anything that works is better than anything that doesn't.
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