[Dovecot] Howto add another disk storage

[Steve Litt]

On Sun, 8 Jul 2012 03:27:55 -0400, Steve Litt said:
> On Sat, 07 Jul 2012 11:36:02 +0200, Reindl Harald said:
> > 
> > 
> > Am 07.07.2012 11:23, schrieb Wojciech Puchar:
> > >>> Fine. i understand that. What i am suggesting is not making
> > >>> large LUNs. you get the best performance with directly
> > >>> attaching disks to your machine.
> > >>
> > >> That's simply not true.  99% of block latency is rotational.
> > >> iSCSI
> > > It's not about iSCSI latency and overhead.
> > > 
> > > It's about other things i just don't want to explain anymore for
> > > people that just have to much money to spent to make things more
> > > complex and less efficient. It's just stupid, but it's OT so EOT
> > 
> > what are you trying to tell us here?
> > 
> > do you REALLY believe you local disks can outperform a
> > SAN storage with 1 GB dedicated buffer cache und a
> > DEDUCATED 1400 MHz CPU which is only optimized for
> > one task: disk performance
> > 
> > you lcal storage has to fight for CPU and memory all
> > teh time with other applications (caching etc.)
> > 
> > to believe under really high load a local storage
> > is faster at the end is bullshit!
> 
> Can one even argue on one side or the other without knowing the speed
> of the network, and how much contention is on that network?
> 
> My experience is that with a 100Mbs network, local is faster, although
> I've never had a SAN, so to speak, on the other end.
> 
> The specification of a SATA rev 3 is 6Gbs, which is a heck of a lot
> faster than 1Gbs per second spec of a gigabit network. Both have a lot
> of things slowing them from their spec, but I'd need to see some proof
> of an assertion that anything coming in over a 1Gbs wire can beat a
> SATA rev3 local disk.

This isn't really a fair comparision because I don't think rev3 is
commodity yet. So Rev 2, which IS commodity, is 3Gbs, which is still
considerably faster than the wire on a Gigabit network.

Thanks

SteveT

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