Re: sata or sas? performance greatly increased with sas?

<markm75c@xxxxxxxxx> wrote:
[...]
It will have this motherboard:
http://www.ewiz.com/detail.php?p=MB-X7DBE&c=fr&pid=879c8a1d895c25a4f05e67f63a192a5d7da30b7da1258398ab50206af2c74e0d
(supermicro)

You may want to consider the Seaburg (5400) models instead of the old
Blackford (5000P), ie X7DW something, but it depends on your exact
requirements.


and use this controller card: (areca arc-1680ix-16 a sas and sata
card) http://www.provantage.com/areca-arc-1680ix-16~7AREC012.htm

I've not used the 1680 but Areca's 1261ML (SAS) controller rocks.

The 1680ix-16 uses a 50% faster CPU version than the 1261ML, but I've
heard that someone was recommended going with the 1231/1261/1280
series instead if they plan to only connect SATA disks to them by
someone at Areca support.

I also know that some other manufacturers SAS RAID controllers pretty
much sucks when connected to SATA disks (it works but performance
isn't there). I doubt Areca 1680 will be *bad* (the CPU is newer and
much higher clocked than the other vendor) but I doubt it will beat
the 1261 series of card either.

Areca's 1680 performance brief suggests they too had some problems in
this area, a number of SATA benchmark is a LOT higher with 1.45
(currrent) than 1.43 firmware. This may have been the cause for that
recommendation so it may well be better now. It's also doubtful if it
would manifest itself with the SAS ES.2 disks, even if the "backend"
hardware is essentially the same as it's SATA cousins.

Either way I assume you're getting the "optional" BBM for the card
(vital) and possibly a memory upgrade (because it may help and doesn't
cost much). The memory upgrade can be a great help if you have a lot
of writes going on.


Right now our existing server has a 3.2TB raid6 array which is pretty
fast with these drives (8 of them): ST3500630NS
http://www.zipzoomfly.com/jsp/ProductDetail.jsp?ProductCode=101923&prodlist=celebros
(500GB 32mb cache 7200 rpm x 8)

Yes, the Barracuda ES series, it's a "RAID" disks (IE higher specs in
some important areas and server optimized firmware) and a pretty good
choice at the time you made that choice. However, ST3500630NS doesn't
have 32MB cache, Seagate says it has 16MB!


So my question is what type of SAS drive would i want to push this
thing even faster.. (dual port? 10k or 7200 with dual port etc).. I'm
not 100% up on sas at this point..

Almost all SAS disks are either 10k or 15k RPM, which does give
benefits. 10k is also available in SATA (WD Raptor) but for "server
loads" it usually looses against the real server disks, and for a VM
server running multiple independent VMs I suspect it's server disk IO
"profile" that fits best.

The drawback is that "normal" SAS disks cost a lot more per GB and
tops out at 450GB (3.5" models). With SATA there's RAID certified
disks up to 1TB (and you definitely don't want the normal Seagate
1.5TB, Seagate has firmware problems on it).


Our one sql server vm, with multiple sql server instances may grow
very large in size, to about 1 or 2TB in size over time, as we move
alot of data into team foundation server 2008 (lots of graphical, vr,
rendering data and images etc).. this is my only thinking for SAS, as
this sql VM will be getting hit more and more (or split the SQL
instances over two VMs on two different hosts)..

I would think even with sql in our environment and running about 8
VM's on each server, we would still be ok with SATA...

2+TB means quite a lot of SAS 10/15k disks, but the performance will
be a lot greater than with 7.2k SATA disks, due to higher performance
per spindle AND more spindles.

You need to decide how much storage you need and how much IO activity
you're going to see, without a detailed analysis no one else is going
to be able to help you.


Here are two SAS drives I've found (500GB variety, though i have yet
to see a 32mb cache equivalent of our sata):

Dual port wise: i dont see many over 500GB in size.. or really any

Single port:
http://accessories.us.dell.com/sna/productdetail.aspx?sku=A1622058&cs=19&c=us&l=en&dgc=SS&cid=27530&lid=627063
(Seagate 7200rpm 16mb cache)

This is Seagate Barracuda ES.2, model ST3500620SS. It's the smallest
model in the SAS ES.2 series, both SAS and SATA ES.2 go up to 1TB...

However, the SAS models have 16MB (same as your ES disks) and the SATA
models 32MB cache. Since there's no other differences you'll see at
least as good performance from the SATA ES.2 and probably slightly
better in fact (assuming no controller bottleneck).

So unless you're willing to go with a larger number of 10k/15k SAS
disks there doesn't seem to be any upside at all with going with SAS.
The disks are very similar and probably run similar firmware so even
the MTBF and other factors should be close to identical.

There IS a significant extra cost for the SAS models compared to the
SATA models so I know which one I would be using (except heavy duty DB
servers which ends up with a pile of 15k SAS disks in RAID10, they
tend to not need that much storage but craves IOPS).

http://www.seagate.com/www/en-us/products/servers/barracuda_es/barracuda_es.2/

For dual port you're really going for FC disks, with the capacity
drawbacks I mentioned earlier (only 10k/15k disks) and in addition
you'll pay a lot extra for it being FC. But whatever floats your boat :-)

It probably makes sense for large arrays where even FC disks are a
small fraction of the cost of the array.
.

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