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RAID VS AHCI

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September 27, 2011 2:44:30 AM

Hello,
I am in the middle of a build where I have a 60GB SATA III SSD as the boot drive and 2 (not identical) SATA III hard drives for programs/storage. Would I be better off setting up the hard drives as RAID or AHCI? Also, I would appreciate ANY tips on how to optimize the system for performance. I have an ASUS Sabertooth P67, i5 core 2500K, and 8gig of memory running Win 7 Pro 64-bit.

More about : raid ahci

a b G Storage
September 27, 2011 2:50:19 AM

Raid (0, 1, 5, 10 & so on) will require 2 or more of the same drives. (identicle model is best but not required)
e.g. 2x 60gb SSD's or 2x 1tb HDD's

AHCI will be what u want.
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September 27, 2011 3:41:58 AM

Quote:
Raid (0, 1, 5, 10 & so on) will require 2 or more of the same drives. (identicle model is best but not required)
e.g. 2x 60gb SSD's or 2x 1tb HDD's

AHCI will be what u want.



Thanks, Hugo........that's what I expected. Would I be better off to buy another "identical' HDD and make it a RAID 0 OR 1? I think I should look into TRIM in Win 7.
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a c 167 G Storage
September 27, 2011 4:20:56 AM

Raid-0 shows up well in synthetic synthetic benchmarks, but not in real app performance. It really is not worth it for the normal desktop user.

AHCI is a subset of raid, so you could specify raid, and you will get trim for the ssd, so long as it is not part of a raid array.

But, I suggest you keep it simple and set the sata mode to AHCI, and install your two drives as simple separate drives.

The value of raid-1 and it's variants like raid-5 is that you can recover from a drive failure quickly. It is for servers that can not tolerate any interruption.
Modern hard drives have a advertised mean time to failure on the order of 500,000+ hours. That is something like 50 years.
With raid-1 you are protecting yourself from specifically a hard drive failure. Not from other failures such as viruses, operator error,
malware, fire, theft, etc.
For that, you need external backup. If you have external backup, you do not need raid-1
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a c 289 G Storage
September 27, 2011 1:21:27 PM

+1 to Geofelt. Most users have no need for the specific advantages of RAID, and it's not worth the effort to use it unless you want to simply play with it to learn something. Simple systems are easier to maintain.

As a side note, I just wrote a full-page rant against RAID for simple builds. Then I didn't post it, to keep my hide from being scorched.
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a c 167 G Storage
September 27, 2011 1:27:20 PM

WyomingKnott said:
+1 to Geofelt. Most users have no need for the specific advantages of RAID, and it's not worth the effort to use it unless you want to simply play with it to learn something. Simple systems are easier to maintain.

As a side note, I just wrote a full-page rant against RAID for simple builds. Then I didn't post it, to keep my hide from being scorched.


I would love to read your raid rant. Post it somewhere along with a link. Perhaps I can add to it.
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September 27, 2011 2:05:18 PM

WyomingKnott said:
+1 to Geofelt. Most users have no need for the specific advantages of RAID, and it's not worth the effort to use it unless you want to simply play with it to learn something. Simple systems are easier to maintain.

As a side note, I just wrote a full-page rant against RAID for simple builds. Then I didn't post it, to keep my hide from being scorched.


I'd also be interested in reading this. Generally I'm against RAID unless there is no other reasonable alternative to what you want to do. Rarely do people need the increased speed, and all the benefits of raid can be had without the risk with various other solutions (Raid 1 vs. nightly automatic incremental backups for example)
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a c 289 G Storage
September 27, 2011 5:15:25 PM

Unfortunately, writing the rant the first time got it out of my system. All that's left is the technical arguments against using <thing x> if you don't really need it.
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June 18, 2012 5:50:48 PM

You need to specify RAID if you want to use any SSD for SRT caching, I think.

Is there ANY disadvantage to specying RAID, as long as you don't put any SSD in a multi-disk RAID array?
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a c 167 G Storage
June 18, 2012 6:03:56 PM

ratsa said:
You need to specify RAID if you want to use any SSD for SRT caching, I think.

Is there ANY disadvantage to specying RAID, as long as you don't put any SSD in a multi-disk RAID array?


You should be OK.

AHCI is actually a subset of RAID. I think the latest Intel drivers will pass on the trim command to a ssd that is not part of the array. For this, you will want to use the intel drivers, not the default windows drivers. I do not know if you will get the proper drivers by default, or if you need to explicitly find and implement them.

But, I think you need a specialized situation to get a great benefit from SRT cancheing.
You need an activity pattern that will load the ssd with data that you will then repeatedly access for some time, and later be reloaded with another set to be repeatedly used.
If you know what you will use, then it is better to put it in a larger ssd to begin with.

I think it would usually be better to use a normal ssd as an os or storage drive.

You can buy a specialized intel 313 20gb slc ssd for use as a srt cache, but it will cost as much as a 64gb ssd.
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June 18, 2012 7:17:32 PM

I will be using a 256GB SSD for OS, Programs and Lightroom Catalogue.

A separate 4 TB will store photos and videos. I may add an SRT cache to this drive. From what I've read, I don't think SRT chaching would be very good in this type of situation.
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June 19, 2012 5:42:02 PM

Hi, Does anyone know if you can use 2x SSD's in a dual bay laptop with completely different controllers???
NOT in a RAID-0 array!
Many Thanks for any replies...
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a c 167 G Storage
June 19, 2012 9:30:18 PM

Dandy007 said:
Hi, Does anyone know if you can use 2x SSD's in a dual bay laptop with completely different controllers???
NOT in a RAID-0 array!
Many Thanks for any replies...

Don't know why not.
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June 21, 2012 9:43:56 AM

Well? As they both have different controllers ie; "Marvel" & "SandForce"...
They use Different DRIVERS do they not?
Are The "Drivers" COMPATIBLE on 1 laptop?
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January 18, 2013 1:09:09 AM

geofelt said:
Raid-0 shows up well in synthetic synthetic benchmarks, but not in real app performance. It really is not worth it for the normal desktop user.

AHCI is a subset of raid, so you could specify raid, and you will get trim for the ssd, so long as it is not part of a raid array.

But, I suggest you keep it simple and set the sata mode to AHCI, and install your two drives as simple separate drives.

The value of raid-1 and it's variants like raid-5 is that you can recover from a drive failure quickly. It is for servers that can not tolerate any interruption.
Modern hard drives have a advertised mean time to failure on the order of 500,000+ hours. That is something like 50 years.
With raid-1 you are protecting yourself from specifically a hard drive failure. Not from other failures such as viruses, operator error,
malware, fire, theft, etc.
For that, you need external backup. If you have external backup, you do not need raid-1


I completely disagree with you on this. Im running a 120gb ssd for my os and 2 HHDs drives in raid 1 for storage. Although generally modern HHDs do last very long there is always the chance of a failure. I have had HHDs die without warning for no reason before (well one but the loss that resulted was terrible). I back up to an external as well but i still think raid 1 is a good idea. I will soon be wiring to another external in the shed incase of fire.

Heres an example that could happen to someone who just uses there computer for normal stuff, not a server or anything...you return from an epic tour of Europe and load the 1000s of once in a lifetime pictures you took off your camera onto your hard drive and then clear your memory card. Later that evening your hard drive fails but it hadnt backed up to the external yet. Although the chances of something like this are probably very low i think the inexpensive extra drive is worth the peace of mind.

In addition to that if a drive fails i dont have to go through the trouble of restoring all my data from the backup drive and my computer wont be down while i do it.

I actually had my SSD fail on me and now im considering running raid 1 SSDs for the OS because the hours of restoring the OS, drivers, programs, etc is aggravating. Although i may just image the drive once i have it the way i like since i dont store anything on it.

I was here looking to see if running in RAID would negatively affect the SSD thats not part of the raid set because this is the second OCZ ssd to fail me in two years. I have now switched to a high end intel one, hopefully that solves the problem.
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a c 167 G Storage
January 18, 2013 1:23:48 AM

KNO3- said:
I completely disagree with you on this. Im running a 120gb ssd for my os and 2 HHDs drives in raid 1 for storage. Although generally modern HHDs do last very long there is always the chance of a failure. I have had HHDs die without warning for no reason before (well one but the loss that resulted was terrible). I back up to an external as well but i still think raid 1 is a good idea. I will soon be wiring to another external in the shed incase of fire.

Heres an example that could happen to someone who just uses there computer for normal stuff, not a server or anything...you return from an epic tour of Europe and load the 1000s of once in a lifetime pictures you took off your camera onto your hard drive and then clear your memory card. Later that evening your hard drive fails but it hadnt backed up to the external yet. Although the chances of something like this are probably very low i think the inexpensive extra drive is worth the peace of mind.

In addition to that if a drive fails i dont have to go through the trouble of restoring all my data from the backup drive and my computer wont be down while i do it.

I actually had my SSD fail on me and now im considering running raid 1 SSDs for the OS because the hours of restoring the OS, drivers, programs, etc is aggravating. Although i may just image the drive once i have it the way i like since i dont store anything on it.

I was here looking to see if running in RAID would negatively affect the SSD thats not part of the raid set because this is the second OCZ ssd to fail me in two years. I have now switched to a high end intel one, hopefully that solves the problem.


True, that is a scenario where raid-1 might have helped.
The problem is, that in that scenario, you made a mistake.
1. Don't delete anything you value until you have an external backup. And, if you are really paranoid, have proven that the backup can be restored.
2. Your external backup must be done on a frequency that is appropriate to irreproducible data.

And... what if instead of a hard drive failure, a virus wiped your duplicated data or perhaps you had a fire.
In those cases only a good external and timely backup would have saved you.

Actually, though, my response was to suggest that the performance value of raid-0 was overhyped.
I found no real world performance benefit from two SSD drives in raid-0. I did, however accomplish my objective of doubling my "C" drive image.
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a b G Storage
January 18, 2013 5:25:15 AM

I had my RAID 1 for HDDs some years ago, but after a BSOD my MFT crashed a I had to recover the data and lost a lot. I personally always to regular scripted backups of my data and delete pictures after backup from my CF cards.
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