Subject: Re: [vserver] Sponsoring VServer getting up to date with mainline
From: Herbert Poetzl <herbert@13thfloor.at>
Date: Fri, 22 Aug 2008 20:20:16 +0200

On Fri, Aug 22, 2008 at 06:57:55PM +0100, Ed W wrote:
> Herbert Poetzl wrote:
> >situation: one of my raid controllers suddenly failed
> >and I need to replace it with a new one (currently
> >the raid is offline, and I don't have access to the
> >data). as I was not very happy with the controller
> >(an Intel/LSI one, which only caused issues from the
> >beginning), I want to replace it with a different
> >model from Adaptec (specifically the RAID 31605), 
> >which seems to have good support and all the features
> >I am looking for.
> 
> Just an aside, but can I ask why a fancy raid controller?

that's simple, with 12+ disks you have almost no
chance to attach them to _any_ motherboard ...

besides that, normal SATA controllers do not have
the bandwith to get performant I/O over e.g.
port multipliers, so the only choice is a big
throughput raid controller ... note that I could
live without the fancy hardware raid features,
but you really don't get any 8-16 port SATA
controller without hardware raid ...

note that disk I/O is the main bottleneck of
todays servers/machines, and compiling kernels
means moving a lot of data from/to disk

> I personally LOVE the top end stuff, for example have some very good
> experiences with Compaq battery backed scsi controllers. But I have
> had nothing but disappointment with even decent 3Ware controllers
> and I notice no difference at all over builtin SATA controllers,
> which coupled with a nice motherboard often mean you can have 8-10
> controllers right on the bridge and hence high speed access
> 
> Battery backup is missing off the onboard controllers though and if
> you have a DB application (probably not if you are getting 1.5GB
> disks) then this is a big deal, but otherwise it's not likely to make
> much difference (hey not teaching you to suck eggs - I'm sure you
> already know if it will help your workload!)

yes, as mentioned, it definitely helps my specific
workload to maximize disk I/O and minimize latency

> In summary though unless you need the battery backup I would recommend
> a new motherboard with enough onboard ports to meet your needs -
> forget what I have but I bought some bits of the office machine and it
> supports my quad intel thing with I think 8+ sata ports?

> > and I could
> >also make good use of three or four of those new
> >1.5TB SATA disks from Seagate (ST31500341AS) or the
> >1TB models (ST31000340AS) to retire one of my older 
> >disk arrays (150-200 USD/ 120-150 EUR each)
> 
> The 1.5TB have quite a price hike, even the 1TB are I think slightly
> above the sweet spot still? I just bought 5x 1TB drives and the
> Samsung spinpoints were the best value - not had any problems with
> them so far, but don't load them much either.

the 1TB disks specified above have 32MB cache, 5 years
of manufacturer warranty, they don't suck power, and 
most important, this series has been working for me
for some time now (the price is roughly 0.12 EUR/GB,
where e.g. a U320 SCSI disk ranges at 1.2 EUR/GB :)

note that the Samsung F1 Raid costs more than the
Seagate model, and I'm not convinced about the SpinPoint
series, as they had bad publicity (overheating and such)

best,
Herbert

> Ed W