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AHCI vs RAID


Harroguk
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Please excuse the ignorance here, I have done some searching and can't really find a definitive answer.

 

At the moment I am running 4x 4TB WD Red in RAID5 (One logical Disk for OS and one for Data).

 

Eventually I plan to move to 4x4TB WD Red in RAID5 (For Data) and 1x 256GB SSD (for OS)

 

From what I am reading, in order to move to the SSD (for OS) I will need to run in RAID mode but currently I "could" be running in AHCI?

 

But just what is the difference? Other posts here seem to indicate there is no performance increase so just why would I choose AHCI over RAID or indeed RAID over AHCI?

 

Thanks

 

Harroguk

 

 

Sent from my iPad using Tapatalk HD

Edited by Harroguk
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People who don't want to run RAID may want to use AHCI. Many of these people use a 3rd party drive pooler, like DrivePool or DriveBender, to pool individual drives into single volume.

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Yeah, I get this, but, why would people choose one or the other? I can't find any benefits or Pro/con list of either system.

 

 

Sent from my iPad using Tapatalk HD

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HP also has hardware RAID products, usually found in higher-end models, and the B120i provides consistency (in deployment or management), I would guess. 

 

For home users the biggest benefit seemed the integration wilh ILO and fan management.

Edited by Royco
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Yeah, I get this, but, why would people choose one or the other? I can't find any benefits or Pro/con list of either system.

 

 

Sent from my iPad using Tapatalk HD

 

I could be wrong and I ask anyone to correct me if needed.

 

AHCI is recommended and supported on all motherboards nowadays.

 

You should enable AHCI (instead of IDE mode which is older and slower). I believe you need to set this up before installing an operating system.

 

But AHCI and RAID are not mutually exclusive.

 

If you're using RAID, your disks could be in AHCI compatible, RAID mode. It depends on your mobo.

 

 

Now keep in mind RAID has its own purposes. You will use it if you absolutely need redundancy.

 

Also it comes in many flavors and types. Firmware Software, hardware, OS-level software (examples: drive pool, storage spaces, ZFS) or 3rd party Application level (drive bend , snap raid).

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I have to say that every mobo I've used that has onboard RAID only gives the choice, in the BIOS, between AHCI and RAID. I'm pretty sure I don't have one that offers a combo of the 2. I wonder which ones might.

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Ikon,

 

I couldn't remember where i read that so i made some searches and this is the best i could find

 

http://www.tomshardware.co.uk/answers/id-2162407/raid-array-work-ahci-mode-bios.html

 

By pinhedd:

"On Intel motherboards, enabling RAID for the chipset storage controller also enables AHCI. Non-member disks (disks that are not part of a RAID) will run in plain AHCI mode, while member disks will run in an AHCI compatible RAID mode."

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"From what I am reading, in order to move to the SSD (for OS) I will need to run in RAID mode but currently I "could" be running in AHCI?

 

But just what is the difference? Other posts here seem to indicate there is no performance increase so just why would I choose AHCI over RAID or indeed RAID over AHCI?"

 

 

Harroguk,

 

From what i gather (from reading http://homeservershow.com/forums/index.php?/topic/5886-gen8-25-hdd-in-the-odd-bay-discussion/page-5), to boot from the ODD sata port with an SSD, you need the raid controller and you need to enable RAID 0 for the SSD.

 

And that's a requisite. And a trick people found and use as a workaround.

 

Not because it gives any better performance.

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Ikon,

 

I couldn't remember where i read that so i made some searches and this is the best i could find

 

http://www.tomshardware.co.uk/answers/id-2162407/raid-array-work-ahci-mode-bios.html

 

By pinhedd:

"On Intel motherboards, enabling RAID for the chipset storage controller also enables AHCI. Non-member disks (disks that are not part of a RAID) will run in plain AHCI mode, while member disks will run in an AHCI compatible RAID mode."

 

Thanks for this. I've never seen it before. From what you posted, it seems like  Intel RAID is a subset, or added feature, of Intel AHCI. Perhaps that also applies to the MicroServers.

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