Ext4 + barriers=1 + ssd + power loss while commiting to a git repo = broken repo?

[Pasi Kärkkäinen]

On Thu, Apr 14, 2011 at 08:59:49AM -0500, Eric Sandeen wrote:
> 
> >> What kind of SSD is it?
> > 
> > OCZ Vertex 2 with firmware 1.25 (this is not the latest version, but I
> > did not have too much courage to update it :))
> 
> Ok.  We (the ext4 list) had a report a year ago or so where someone had really debugged some odd behavior with one ssd and its firmware, but not this one :)
> 
> So not the same thing exactly, at least.
> 
> > 
> > Do the barriers are somehow dependent on the hardware? Maybe I need to
> > look in the SSD documentation to find out if proper commands are
> > supported?
> 
> I don't think you'll find that sort of thing; it's a question of implementing the spec properly, really.  All I meant is that it is -possible- for hardware to be broken or noncompliant, so it's -possible- that that's what you're seeing.  I'm NOT saying that the OCZ-VERTEX2 -is- broken, just musing that the hardware needs to exhibit proper behavior as much as the application needs to issue the right data integrity syscalls.  :)
> 

I remember reading on the ZFS list that the consumer Vertex2 models do not have a 
battery backup (or a supercapasitor) to flush the internal cache in the case of power loss.

So they'll corrupt the data in the case of power loss..

-- Pasi