20 Bay Raid 5 Controller

[leasoncre]

What controllers are the cheapest to the best for running RAID 5 with 20 Hard drives?

I plan on getting this case: (Norco RPC-4020)
http://www.google.com/products/catalog?cid=15526599328051592981&q=RPC-4020%2B4U%2BServer%2BCase%2Bw%252F%2B20%2BHot-Swappable%2BSATA%252FSAS%2BDrive%2BBay
with these hard drives: (WD20EARS)
http://www.google.com/url?q=http%3A%2F%2Fwww.directron.com%2Fwd20ears20pk.html%3Fgsear%3D1&usg=AFQjCNFjJPKkENBiHq5XwtZq1uOfjRqMaA

and i was looking at HighPoint's RocketRaid Cards (DL'd PDF file) (they're expensive) specifically:
HighPoint RocketRAID 3560 24-Channel PCI-E x8 SATA2 RAID Controller
http://www.google.com/url?q=http%3A%2F%2Fwww.superbiiz.com%2Fdetail.php%3Fname%3DHI-RR3560%26src%3DFR%26pid%3D458e93c86fbe5e916c15d32209b3e8b3f980756b7b182a574fe43df9647a8bf8&usg=AFQjCNG8WFqzzyYdMb6b6C2qmHCfzV7GyQ

1. I was wondering if there were any quality cards at a cheaper price out there?

2. PS. i assume that a mini-SAS connection (SFF-8087) translates into 4 SATA connections. from what products i have seen, this is what i understand. correct?

3. Also what Power supply would one recommend for above system: 600W - 1000W?

This would be my first venture into Server Raid systems
Let me know if there is anything else i should know about Server RAID systems.

i also realize ( http://www.tomshardware.com/forum/257590-32-wd20ears-safe-raid ) i may not be able to use said drives for this. if i can't find 2TB drives for under 100ea for this task, i may just have to wait. (dang-it)

 

[MRFS]

WD's Caviar Greens do not support TLER (time-limited error recovery):
their RAID Edition ("RE") drives do support TLER.

DON'T BUILD A RAID WITH CAVIAR GREENS!

If you must have 2TB HDDs, here's the drive we highly recommend
for a large 20-drive RAID:

http://www.newegg.com/Product/Product.aspx?Item=N82E16822136579&Tpk=N82E16822136579


Yes, there is a SFF-8087 cable with "fan-out" SATA connectors e.g.:

http://www.newegg.com/Product/Product.aspx?Item=N82E16816103194&Tpk=N82E16816103194

We use a similar cable from Highpoint to connect the RocketRAID 2720
to 4 x 2.5" Hitachi HDDs in an Enhance Tech X14 enclosure, and
it works very well.


If your controller does not come with those cables,
you'll need to purchase them separately e.g.
Highpoint have a cable matrix at their website.


For 24 drives, you're going to need something
like the Highpoint RocketRAID 2760:

http://www.highpoint-tech.com/USA_new/series_rr2700.htm
http://www.newegg.com/Product/Product.aspx?Item=N82E16816115081&Tpk=N82E16816115081
http://www.highpoint-tech.com/PDF/rr2700/Datasheet%20for%20RR2760_050710.pdf

6 x SFF-8087 mini-SAS = 24

This is one of the few that uses a full x16 mechanical slot.


Or, Areca are another high-quality RAID controller
that will satisfy your needs, but probably for a much
higher price.


To "future-proof" your purchase, I would definitely go with support for
6G SAS/SATA, so you can migrate later to 6G SSDs (SAS or SATA)
which are right around the corner e.g. Sandforce SF-2000 series:

http://www.legitreviews.com/article/1429/1/


Hope this helps.


MRFS

 

[MRFS]

> Also what Power supply would one recommend for above system: 600W - 1000W?


For the WD2003FYYS, figure 10.7 W for each drive:

http://www.wdc.com/en/products/products.asp?driveid=732

Electrical Specifications
Current Requirements
Power Dissipation
Read/Write 10.70 Watts
Idle 8.10 Watts
Standby 1.50 Watts
Sleep 1.50 Watts

20 @ 10.7 W = ~214 Watts

And add ~50% if your controller and HDDs do not support
staggered spin-up: the largest amp load will occur during spin-up.

So, any good 750-850W PSU should power the entire server easily
assuming you don't go hog-wild with multiple video cards
(not usually the case with servers anyway

The sweet spot (max efficiency) for most modern PSUs
is at or near 50% utilization. See the detailed efficiency graph
for full details.


MRFS

 

[MRFS]

> This would be my first venture into Server Raid systems
> Let me know if there is anything else i should know about Server RAID systems.


I urge you to hire a server expert, like my colleague Roger Shih,
President of Micro City, Inc. in San Diego:

http://www.microcityinc.com/

Roger has been building high-performance servers for years,
and he's a wonderful man as well.

English is his second language, but don't let that bother you.

Whenever Roger speaks, I LISTEN!!

FYI: he'll probably steer you to an Areca controller, because
Areca support RAID 6, which would be a good idea for that
number of HDDs (20+).

Even if you just hire Roger for advice and consultation, HE'S WORTH IT!!


MRFS

 

[leasoncre]

thanks for the excellent information!

 

[sminlal]

I hope you're not intending to build a single large 20-drive array. Several small arrays of, say, 4-5 drives each would probably be OK, but a huge 20-drive array is a very BAD choice to use with RAID-5.

The problem is that if ANY drive fails and you swap it for a new drive, the RAID controller has to read EVERY sector from EVERY other drive in order to rebuild the data. With that much data this will take a long time (days) during which performance will be very poor, and the chances of hitting an unreadable sector during that time are pretty high, in which case ALL your data is toast.

For a very large array you should use RAID 6 instead.

 

[Gatorbait]

I would suggest you buy a Drive box that has an expander in it. This way you will only need a mini-sas 4x cable from your card to the drive box. In addition you will not need a 24 port SAS/SATA RAID card, but a 4/8 will work fine. A bonus is that you will only need one cable. Get a SAS 6gig card so that the path to the expander will be 6gig x4 that way you will not have a bottle neck. (expander should support 6-gig on drive back plane). LSI / 3ware also makes the RAID cards. HP, Dell, IBM, LSI, and many more make drive boxes with expander. LSI cards will support RAID6 as well.

 

[leasoncre]

I would suggest you buy a Drive box that has an expander in it. This way you will only need a mini-sas 4x cable from your card to the drive box. In addition you will not need a 24 port SAS/SATA RAID card, but a 4/8 will work fine. A bonus is that you will only need one cable. Get a SAS 6gig card so that the path to the expander will be 6gig x4 that way you will not have a bottle neck. (expander should support 6-gig on drive back plane). LSI / 3ware also makes the RAID cards. HP, Dell, IBM, LSI, and many more make drive boxes with expander. LSI cards will support RAID6 as well.

could you recomend some links with that?
i didn't quite understand some of that. what's an "expander?" the SAS-to-(x4)SATA cable?
whats the "Drive box?" the case?
by 6gig do you mean SATA 3.0 6Gbs?

thanks.

 

[Gatorbait]

An SAS/SATA expander is an IC that talks with a host SAS/SATA controller and expands the ports from 4 -> 24.
Yes, 6gig is SAS 6.0Gb/s or Sata 3 6Gb/s.

Here are some examples of JBODs/cases that have Expander inside:
JBOD: http://www.lsi.com/storage_home/products_home/jbods/index.html

LSI/3Ware RAID Cards:
http://www.lsi.com/storage_home/products_home/internal_raid/megaraid_sas/index.html