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Running RAID5 on Z68 across SATA 2/3 - How would you set this up?

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June 24, 2011 7:59:09 PM


Hi I'd love some thoughts on this if you have a second.

Setup: Z68 motherboard - likely a Gigabyte GA-Z68X-UD3H.

This board has 2 SATAIII via the Z68, 4 SATAII via the Z68 (3 if the eSATA is active) and 2 SATAIII via the Marvell 88SE9172 chip.

Drive setup: 1 SATAIII SSD (system drive), 3 Seagate 2TB Green SATAIII, 2 SATA DVDs.

So the question is what is the best way to configure the drives? Obviously I want to run the Seagates in RAID5 - however since you can't RAID across Intel/Marvell, I can't take advantage of SATAIII speeds for those drives.

Will there be any noticeable difference running a SATAII RAID5 vs if I had a true SATAIII RAID5 option?

Should I put all 3 Seagates on SATAII or 2 on the SATAIII and 1 on the SATAII?

Is there any disadvantage to running the SSD System drive on the Marvell? Is there any disadvantage to running it on the same controller as the RAID?

Thanks for you advice - note this has nothing to do with Intel SmartResponse SSD Caching which will be disabled because it is a 128GB SSD.
June 24, 2011 8:29:48 PM

Seems the key part here is where the RAID-5 array goes, and the remaining devices can be fit accordingly afterward. I'd setup the 3-HDD RAID 5 array on the SATA-2 ports. Gigabyte itself warns that "When a RAID set is built across the SATA 6Gb/s and SATA 3Gb/s channels, the system performance of the RAID set may vary depending on the devices being connected." Sounds as if they're worried about a bit of "wonkiness" there... To view their warning, scroll down to the "Storage Interface" section here.

SSD = SATA-III Z68
RAID-5 Array = SATA-II Z68
Optical drives = Marvell

Most high-performance HDD's can't even saturate a standard SATA (1.5Gb/s) channel, let alone a SATA-II channel. There's certainly no need for them to occupy any of the SATA-III ports.
a b G Storage
June 24, 2011 8:54:38 PM

You may want to look into the Z68 SSD caching and quick save. This allows you to get speed advantages of SSD while utilizing the mass storage of regular drives. In this setup you would use your SSD as a cache for your RAID5 array. Unlike typical RAID5 which has a write penality, with caching you will write out to the SSD and the changes are migrated to the RAID5 over time (transparent to the OS). This will give you the best of both worlds. It is extremely similiar in concept to the Compellent enterprise class storage systems Dell recentlysquired.
Related resources
a b G Storage
June 24, 2011 10:11:55 PM

Correction: Unfortnately the Z68 feature does NOT eliminate the write penalt as the Compllent solution does, this makes the cachine much less appealing if write performance is important.
a b G Storage
June 25, 2011 7:48:35 AM

RAID5 performance is going to be painfull in that setup

Intel ports will always be quicker - its Intel

some of the external chip sata/ide controllers will not work for dvd's aka installing windows using them

also take note RAID's do NOT cover boot sector corruption, data corruption, virus's, accidental deletion etc - its not designed to replace a propper backup solution, its there to protect against single drive failure with minimal/no down time
June 28, 2011 10:48:17 PM

Thanks for the tips everyone.

apache_lives - why do you say RAID5 performance will be painful?

I am planning to run RAID5 for the redundancy more than the striping performance. I realize RAID5 won't give me the performance of RAID0 but it shouldn't be poorer performance than a standalone hard drive should it?
a b G Storage
July 5, 2011 8:06:04 AM

Use SPM393
You can have raid5 in 45sec and fast, close to 210Mb/sec
Not drivers need, it needs a SINGLE SATA port as AHCI (work best). OS will see as a SINGLE, FAST, BIG drive
a b G Storage
July 6, 2011 4:14:08 AM

RAID 5 will be painful for writes and yes it will be slower than a single drive in write performance but better than a single drive for read performance and will also consume CPU time since you are not using a hardware RAID controller.
July 6, 2011 7:18:27 AM

Actually, write speed should be damn near identical to single drive speed, and read speed will double.

And just how is this not hardware RAID if it's controlled by the southbridge? Granted, it's not a controller card that's seen as a logical disk, but it's certainly far from OS configured software RAID.

I think the real performance concern here might be just what kind of performance to expect from "Green" HDDs within a RAID-5 array. I've seen quite a few people complain about RAID performance of WD Caviar Green HDDs.
a b G Storage
July 8, 2011 3:24:36 AM

The difference is that firmware based RAID offload the XOR calcs to your main CPU unlike hardware RAID... Hardware RAID means having a dedicated processor for XOR and dedicated cache on the controller. I don't consider southbridge crontroller RAID hardware RAID.
a b G Storage
July 8, 2011 3:32:00 AM

And writes will be no where near identical.
!