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Boot drive(s) in Raid1

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October 6, 2011 4:21:08 AM

I'm getting a new Win7 PC that will have a single 1TB drive on an ASUS P5G41T-M MoBo. My plan is to reformat the 1TB into a storage drive, get 2 SSD drives which I will set up as Raid-1 boot/program drives, using the supplied OEM DVD to reinstall the OS. My basic question: is this even possible, having two identical boot drives in Raid1? If so, how do I accomplish it? How does the OS decide which drive to boot from?

Thanks.

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a c 523 G Storage
October 6, 2011 5:18:22 AM

A RAID-1 array is 2 or more physical drives combined to create 1 logical drive.

So Windows "sees" only 1 drive, regardless of how many drives you used to create the RAID array.

The Asus motherboard you listed does not support RAID. If you have not purchased it already, upgrade to another model.
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October 6, 2011 11:41:19 AM

Phooey! Thanks for the good-news-bad-news. Yes the system is already purchased and arriving soon.
Any software or hardware work-arounds?
Thanks again.
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a c 523 G Storage
October 6, 2011 1:47:16 PM

Yes. There are 3 ways you can create a RAID array.

1.) Software RAID. You can create a RAID array via Windows 7.
2.) Firmware RAID. You can create a RAID array via your motherboard BIOS. This is the most common method used to create a RAID array.
3.) Hardware RAID. You can create a RAID array via a add-in card that plugs into a PCIe slot on your motherboard.

Method 2 is not available to you. You get the best performance and stability with methods 2 & 3 since the RAID array is created at the BIOS level, but method 1 is free.
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October 6, 2011 4:25:42 PM

If you are purchasing two SSDs, I highly recommend RAID0 and a secondary backup solution.

Unless you run a server that absolutely cannot have any downtime, I don't see the point in using RAID1 for a boot drive. RAID1 is simply mirroring, and both drives will be exactly the same. You will lose the storage capacity of one of the SSDs (kind of a waste at the price/GB SSDs cost nowadays) and you will find no performance increase.

Having two identical boot drives (if you're not running a server) is pretty pointless. What I recommend is putting them both in RAID0 (striping only) where you will see both (theoretically) a DOUBLE in performance and a (actual) double in capacity. I'm not sure how well RAID0 boot drives would work if you're using software RAID, but it should still be much faster than a single drive working by itself.

If you set up the boot drive method as RAID0 and had a secondary, in-OS backup solution (like Acronis) to backup images of your boot drives, you will have both a backup solution AND double your speed and capacity. I see this as a double win, whereas using RAID1 for your boot drive is kind of pointless, especially since they are solid state drives, with very little failure rate (as opposed to a mechanical drive, which has a much higher failure rate - but you shouldn't really have to worry about SSDs failing, not for under a decade).
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October 7, 2011 3:29:22 AM

Thanks to Dereck47 for your clear explanation of my options and to gkalavik for making me rethink my plan. Reading about SSDs convinced me that reliability and longevity is not a given, hence my desire for redundancy in a boot/program drive. But now I see that I can have the same insurance at less cost via ghosting rather than Raiding the SSD. In fact, I have my eye on the latest Samsungs that come packaged with Norton Ghost. Apparently that manufacturer is thinking along the same lines. {EDIT: Samsung's main purpose for including NG seems to be data migration TO the SSD rather than backing up the SSD.}

Raid-0 doesn't interest me at this time, since SSD performance is more than great for my purposes, and I have that 1tb drive for storage -- including the boot drive image.
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October 7, 2011 4:00:30 AM

njride,

Do not use SSD's in RAID-1, it turns into a lose / lose scenario. SSD's rely on naitive OS TRIM commands to maintain high levels of performance, otherwise they'll eventually get cluttered and start to have degraded performance. Using a RAID on SSD's prevents the OS from sending TRIM commands to the individual disks which in turn ends up degrading the device's performance. Contrary to popular belief RAID-1 will provide enhanced read performance as the HBA will be reading from both disks, but write performance will be slightly worse then normal as the HBA must commit two disk writes for each system write issued. Unless your using a specialized controller with specialized logic (Fusion-IO / OCZ RevoDrive), SSD's should never be RAID'd.

What you can do is use the SSD as an OS partition and the 1TB disk as your data partition. With NTFS you can even mount the HDD under a folder name instead of a disk. So C:\ is the SSD, but C:\Games is the HDD.

I would suggest getting a separate 2TB external disk, either eSATA or USB, and use it as your backup disk. It should be detachable so you can put it away after each weekly backup.

For disk mirroring software I'd recommend either Acronics True Image or Disk Doctor. Although True Image is more "backup" orientated. It will mirror your disk over to an image file and you can maintain multiple image files for different moments in time.
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October 7, 2011 4:49:09 PM

palladin9479 said:
njride,

Do not use SSD's in RAID-1, it turns into a lose / lose scenario. SSD's rely on naitive OS TRIM commands to maintain high levels of performance, otherwise they'll eventually get cluttered and start to have degraded performance. Using a RAID on SSD's prevents the OS from sending TRIM commands to the individual disks which in turn ends up degrading the device's performance. Contrary to popular belief RAID-1 will provide enhanced read performance as the HBA will be reading from both disks, but write performance will be slightly worse then normal as the HBA must commit two disk writes for each system write issued. Unless your using a specialized controller with specialized logic (Fusion-IO / OCZ RevoDrive), SSD's should never be RAID'd.

What you can do is use the SSD as an OS partition and the 1TB disk as your data partition. With NTFS you can even mount the HDD under a folder name instead of a disk. So C:\ is the SSD, but C:\Games is the HDD.

I would suggest getting a separate 2TB external disk, either eSATA or USB, and use it as your backup disk. It should be detachable so you can put it away after each weekly backup.

For disk mirroring software I'd recommend either Acronics True Image or Disk Doctor. Although True Image is more "backup" orientated. It will mirror your disk over to an image file and you can maintain multiple image files for different moments in time.


That's interesting, I hadn't thought of that. But then why do so many people do Raid-0 with SSDs?
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a c 523 G Storage
October 7, 2011 5:50:31 PM

gkalavik said:
That's interesting, I hadn't thought of that. But then why do so many people do Raid-0 with SSDs?


Because all modern SSDs use idle Garbage Collection (GC) independently of TRIM to restore drive performance.
All you have to do is "Log Off" overnight from your pc once or twice a week to maintain drive performance.

Don't know if you know this but up until the latest version Lion that was released, Apple OSX never supported TRIM.
But yet people have been buying SSDs to use in Apple computers for years. :) 

Currently SSDs with SandForce (OCZ, Corsair, OWC, etc.) controllers have the best GC implementation.

Also, I've had 2 SSDs in RAID-0 for over a year and I'm getting 94% of my drive's maximum advertised Read/Write rates.
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October 7, 2011 5:59:54 PM

Dereck47 said:
Because all modern SSDs use idle Garbage Collection (GC) independently of TRIM to restore drive performance.
All you have to do is "Log Off" overnight from your pc once or twice a week to maintain drive performance.

Don't know if you know this but up until the latest version Lion that was released OSX never supported TRIM.
But yet people have been buying SSDs to use in Apple computers for years. :) 


So if you're using modern SSDs, it's okay to put them in RAID-0? I'm not sure if I understand you correctly
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a c 523 G Storage
October 7, 2011 6:05:27 PM

gkalavik said:
So if you're using modern SSDs, it's okay to put them in RAID-0? I'm not sure if I understand you correctly


Yeah, don't worry about it.

Like I said just Log Off before you go to bed or before you go to work once a week.
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October 7, 2011 6:07:55 PM

Dereck47 said:
Yeah, don't worry about.

Like I said just Log Off before you go to bed or before you go to work once a week.


I don't suppose hibernate counts?

I dream of the days when computers are completely self-maintained once you put them together. Having to log off every night *just* to maintain my boot drive is a whole... thing.
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a c 523 G Storage
October 7, 2011 6:09:44 PM

Yes, GC works as long as power is being supplied to the drive.
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a c 523 G Storage
October 7, 2011 6:18:57 PM

Sorry, I was mistaken. In hibernate mode the current state of your system is saved to the drive and it is shut down; so GC will not work.
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October 7, 2011 6:20:25 PM

So one has to log out of their user in Windows, and then GC goes into action? Roughly how long would one have to wait before shutting down/hibernating their system?
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a c 523 G Storage
October 7, 2011 6:33:57 PM

Sorry, I don't know. Too many variables. It would be different for everyone.
The size of your drive, the % of available space on it, the number of files that the O/S has deleted that GC has to recover, the size of those files, etc.

I can tell GC is working on my pc when I log off when I start to see my drive activity light begins to flash on my pc case.
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October 7, 2011 6:42:46 PM

Dereck47 said:
Sorry, I don't know. Too many variables. It would be different for everyone.
The size of your drive, the % of available space on it, the number of files that the O/S has deleted that GC has to recover, the size of those files, etc.

I can tell GC is working on my pc when I log off when I start to see my drive activity light begins to flash on my pc case.


Ah, that bit of info is helpful. Thanks.
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October 10, 2011 2:34:22 AM

Dereck47 said:
Because all modern SSDs use idle Garbage Collection (GC) independently of TRIM to restore drive performance.
All you have to do is "Log Off" overnight from your pc once or twice a week to maintain drive performance.

Don't know if you know this but up until the latest version Lion that was released, Apple OSX never supported TRIM.
But yet people have been buying SSDs to use in Apple computers for years. :) 

Currently SSDs with SandForce (OCZ, Corsair, OWC, etc.) controllers have the best GC implementation.

Also, I've had 2 SSDs in RAID-0 for over a year and I'm getting 94% of my drive's maximum advertised Read/Write rates.



Awhile back Toms did an article on this and it was demonstrated that most drive's GC isn't working so well right now. I'm sure it'll get better as time moves on. OCZ already has a very solid implementation going for them.
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October 10, 2011 4:29:02 AM

palladin9479 said:
njride,

Do not use SSD's in RAID-1, ....


OK, no RAID, one SSD.
Two final questions, if I may:

1- The term AHCI keeps cropping up in connection with SSDs, but my ASUS P5G41T-M MoBo manual does not mention anything about AHCI. I did find on various forums that enabling "enhanced SATA" in the BIOS is "the same as AHCI" but others mentioned that it is not. So does this limit my choices as far as which model SSD to get? Or does it simply reduce performance no matter which model I get?

2- I had assumed that I would be formating the 1tb drive that currently has the Win7 OS, but now I'm wondering if it's actually necessary to do that. Can I install the OS on the SSD as a boot drive and leave the existing OS where it is as a failsafe boot device?

Thanks again.
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October 10, 2011 4:53:46 AM

AHCI stands for Advanced Host Controller Interface.

http://en.wikipedia.org/wiki/Advanced_Host_Controller_I...

It's the standard for talking to storage controllers and their disks without requiring a propriety implementation. Basically it's native SATA.

You need to reference your motherboard manufacturer's manual to know what each setting is. They tend to use different terms but the three you run into the most often are Legacy IDE, AHCI, and RAID. Legacy IDE forces it into IDE emulation mode, don't ever use it unless you planing on installing DOS / Windows 98. AHCI tells it to act like a plain SATA controller, the OS will be able to enumerate and access the disks individually. Windows XP will require a SATA Miniport driver specific to your controller's manufacturer. RAID well have the board's built in RAID firmware initialize and control the disks, the host OS will not be able to enumerate and control the individual disks and instead you can use RAID0/1/10/5 modes. This will require you to load a storage driver so that your OS can talk to the storage controller.

To answer your second question, it depends. How much data have you used on your drive?

Honestly with SDD I would just reinstall and have your older HDD mounted as C:\-Whatever-. I've done OS transfers before and it's not hard, just shrink the volume and image it to the new disk, ensure you copy the MBR, system partition and OS signature. But with you going from a significantly larger disk to such a smaller one, you really need to rebuild.
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October 17, 2011 1:54:12 AM

Best answer selected by njride.
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