[Alienware 17R4] RAID or AHCI for 2 SSDs and 1 HDD?

Hello,

I am planning to add another ssd dedicated to linux. So the resulting setup would be like this:

256GB 950 pro for Linux
128GB M.2 SATA 6Gb/s SSD for Windows 10
1TB 7200RPM SATA 6Gb/s for data

What is the best option for this setup RAID or AHCI? I don't know what these mean but on AW 17 R3 with 950 pro, crystal disk mark shows higher speeds in RAID than AHCI.

Thanks

 

RAID for sure.... contrary to what RAID and AHCI really mean, when it comes to the AW (odd I know) RAID is more so of a newer protocol.

I get better performance with RAID, even when I'm running my solo 1TB Samsung 960 Pro in Bay #2.

@DeeX can also attest to this... RAID all the way. (<--- Newer protocol.)

 

how does RAID with 1 SSD drive work exactly? Don't RAID need multiple identical drive to work?

 

Alienware laptops have always had RAID as default bios settings. Work exactly as ACHI. Due " Direct Media Interface" you won't get faster transfer speed with two NVMe ssd's in raid. Not needed with today's fast NVMe ssd's. Only benefit is a big single partisjon.

 

To enable RAID you need 2 drives of the same size. As far as I'm aware, you will need to configure the drives as RAID 1 (striping) because RAID 0 is mirroring which would prevent you from using one drive for Linux only.

To better understand the difference, striping means data is written across 2 drives instead of one making read and write access much faster. As Papusan said, SSD's are so fast that you don't really need a RAID 1 configuration anymore. RAID 0 is for data safety as everything written to the first drive is automatically mirrored to the second drive. In the event of a drive failure you won't lose any data and once the faulty drive has been replaced you should be back to normal within a couple of hours. If you backup to the cloud or an external drive RAID 0 isn't paramount either but if you cannot risk losing any data whatsoever then it is the best option to take although an extra backup should still be made in case the laptop gets stolen.

 

Are you sure you have your RAID numbers right?

 

Configuring RAID 1 and RAID 0 should be done in the BIOS? In AW 17 R3, I don't see any such option. Are they present in AW 17 R4 BIOS or Does it appear only after inserting multiple drives? or It needs to be done through software in the OS?
Do I have to do anything special for that?

 

On the AW's just stay on RAID. There is no need to keep it at ACHI, unless you're working an old old drive that might need it to be on ACHI.

Other than that, keep it on RAID. Again, it is a newer protocol. Nothing more, nothing less.

 

Actually, I kept it on AHCI for 17 R3 because Ubuntu installer could not see 950 pro in RAID mode. When I change it to AHCI, then only I could select 950 pro in the Ubuntu installer. So I have to see how it goes after receiving AW 17 R4.

 

eadgar, you are correct. I confused the two.
Vikram, you should read this explanation: http://www.diffen.com/difference/RAID_0_vs_RAID_1

I also said that the 2 drives must be the same size but that's because Dell always says that when you are ordering a machine in a RAID configuration. From what I have read this morning, it appears that disks can be of different sizes when using RAID 0 because the RAID array sees them both as 1 disk. If using RAID 1 it is better to use identical disks because one will be a mirror of the other. If you have a 128 Gb drive and a 256 Gb drive data will be mirrored from the 128 Gb drive and the remaining 128 Gb on the 2nd drive will be unusable.

I'm not 100% certain about this because Dell techs always did the configuration for me while on a remote session however, I remember them setting it up in the BIOS. That is setting it to RAID. The part I am unsure about is where they selected RAID 0 or RAID 1 but I believe that once you set it to RAID you are then asked to make that choice. If I am wrong, would someone else please clarify.

FWIW, my previous M17x was configured as RAID 0 using 2x 512 Gb drives for ultra-fast read/write. Because data is critical for me I backed up everything critical on a nightly basis to an external drive. My new R4 is configured as RAID 1 because I had heard too many stories about SSD failures and wanted to be sure I could swap one out without losing data.

 

"data is striped (or split) evenly across all disks in the RAID 0 setup"
I don't understand what data they are talking about. Does it mean that when I install an application, it will be split on different drives according to its whims and fancies? Or I will not be able to differentiate between two ssds on windows or Iinux file explorer? I just want them to function naturally with a common bootloader on one drive and if possible I want to be able to set aside 100 GB from Linux drive and format it as NTFS for installing some Windows games.

 

In a RAID 0 configuration ALL data is striped across the 2 drives so yes, it would be according to whatever Windows decides is the best method of distributing the data.

If you want to differentiate between the 2 drives as though they were regular separate drives you must configure them as AHCI.

As you want a dual-boot system it may be that you can install Linux on the 3rd drive if you partition it so that one partition is set aside for the O/S while any remaining partitions are for data. It has already been formatted as NTFS so you won't need to make any changes there. Having never used a dual-boot system I'm not sure whether what I am suggesting is feasible so perhaps others reading this thread could chime-in...

 

any way to switch from AHCI to RAID without reinstall windows 10?

 

It is done in the BIOS, not in Windows so I can see no reason to reinstall Windows.

 

That is a scenario where you would need it on achi yes.

::iunlock::

 

Changing that directly in BIOS will not let you boot into windows because appropriate drivers will not be loaded. Assuming that you have only single Windows 10 boot. If you have double or triple boot with different bootloader, select Windows as #1 boot priority in BIOS and follow the below steps:

1. Run Command Prompt as Admin
2. Invoke a Safe Mode boot with the command: bcdedit /set {current} safeboot minimal
3. Restart the PC and enter your BIOS during bootup.
4. Change from AHCI to RAID mode then Save & Exit.
5. Windows 10 will launch in Safe Mode.
6. Right click the Window icon and select to run the Command Prompt in Admin mode from among the various options or may be use Windows + R and type in cmd or manually navigate in the windows explorer and find the cmd.
7. Cancel Safe Mode booting with the command: bcdedit /deletevalue {current} safeboot
8. Restart your PC once more and this time it will boot up normally but with RAID mode activated.

Same goes for RAID to AHCI. But for other OSes like Linux etc, I do not know how.

 

You can use msconfig to check safe mode and restart your PC. Go to BIOS and switch to AHCI from RAID or other way around. Then start windows. Safe mode will initiate install of IRST driver shipped with W10. After that, uncheck safe mode in msconfig.
Or you can follow this guide. http://triplescomputers.com/blog/un...ch-windows-10-from-raidide-to-ahci-operation/

 

I had trouble when running my SSD in RAID mode switched to AHCI and haven't had any issues since.

 

Is there a speed advantage for using RAID0 for two NVME SM961 512GB's? There is a case for being able to access two drives at the same time to complete one task should be an improvement, but is it an improvement worth while? I have already done it but with the 6700HQ - Didnt notice a different.

 

Quite rarely you have huge performance improvements from RAID'ing 2 PCIe SSDs. Unless you have super eyes, you wouldn't notice a difference.

 

Yeah, I gathered as much. So no real advantage of having 2 512gb as there is one.

 

RAID does increase boot time compared to AHCI, mine increase by about 10s for BIO. But my 960 Pro went from 2800 mb/s to 3200 mb/s read

 

AHCI is old bios/hardware detection even UEFI is faster I think? But almost 15% faster.. I might RAID0 my spare sm961 after all.

BTW I'm SNEuk.. an acc i'll close if possible.

 

Edit this post. You have your RAID configurations reversed. And no, you don't need to have drives of the same size. To utilize RAID it uses the smallest common denominator. If you have a 512GB and 1TB drive you are going to be able to either run RAID-0 (Stripe) at 1TB total, or RAID-1 (Mirror) at 512GB total. Never mix a RAID array with SSD and HD.

Also, you don't need any of this to have the option turned on, just to utilize RAID arrays.

 

Gents, the real question you should be asking yourself here is: does the AW 17 R4 uses hardware or software RAID?

I don't own an AW 17 yet, and there is not much I can find on this topic. But my best guess is that it is software RAID based on the Intel chipset. This means running two disks in which ever RAID mode is consuming CPU power and memory resources to be able to do so. Only hardware RAID controllers really allow for a performance improvement.

Please note there is a distinctive difference in enableing the RAID in BIOS and actually creating a RAID setup. Just enabling it in BIOS will do not much harm to any resources. Configuring a RAID does.As I don't own an AW yet I cannot advise you yet how to enable RAID on an AW17R4.

Be aware of the big downside of RAID0. Despite the extra capacity and maybe performance increase, you risk loss of all data on both disks if one of the two disks crashes. That is the way RAID0 works.

This will not happen with RAID1. If one of the two disks crashes you can simply replace it with an identical one and it will rebuild itself automatically. RAID1 will give you only data security, it will not give you performance increase and it will to double your storage capacity.

In the old days (I am 39) with only SATA connections RAID0 would give you performance increase, but as with the AW17R4 specifically it has two PCIe m.2 slots. This fact combined with for example a single Samsung EVO 960 pro out-passes any performance increase over a SATA RAID0 setup.

 

If someone can create a Raid 0 and set it up yet not be smart enough to know how to make a backup, then they deserve to lose their data if a drive fails