Re: [SLUG] LVM

[Jake Anderson <yahoo@xxxxxxxxxxxxxxx>]

On 15/06/10 17:10, james wrote:
> On Tuesday 15 June 2010 12:15:52 you wrote:
>    
> > On Tue, Jun 15, 2010 at 11:14:38AM +0800, james wrote:
> >      
> > > The stuff  below is interesting and a reference, but this highlights my
> > > favourite rant: Seagate's 'ATA more than an interface' says multiple
> > > disks in a machine *will* result in a higher failure rate, maybe much
> > > higher.
> > >        
> > Due to heat, or what? That paper seems to concern itself primarily with the
> > differences between PS (personal storage) drives and ES (enterprise
> >   storage), in order to justify why the SCSI drives have so much higher cost
> >   per bit.
> >      
> The bit that says:
> Disk#1 seeks knocking Disk#2, Disk#3 off track
> so
> Disk#2 seeks knocking (mechanical coupling) Disk#1 off track
> so
> Disk#1 seeks again
> etc
>
> my own experience is that n-disk arrays fail more than n times 1 disk
> but that is oh so subjective, and so subject to the ravages of stats.
>
> James
>    
in subjective land disks in arrays are probably used allot more heavily 
than those sitting in singles (IE server Vs Desktop usage)

I understand that server grade disks have accelerometers built in these 
days to pick up accelerations caused by other disks in the stack seeking.

I also recall seeing a video of a really large array (40+ disks in a 
dedicated storage box) in a data centre, they had pulled up a latency 
monitoring tool and then had a guy scream at the drives, this caused a 
noticeable spike in latency