RAID1 technical questions

[Organground]

Hi, for the past year I've been using my twin 1TB disks in RAID0 configuration as I need ultrafast loading into RAM for a certain application I run. Anyway, I decided to give RAID1 a try because of the alleged additional data resilience and see how much slower my software loaded (about two-thirds the speed, it turns out). Anyway, I'm wondering whether to continue RAID1 or revert to RAID0 and have a few questions that I'd appreciate advice with.

1. If I have a PCS machine running two identical disks as RAID1 and one disk packs up, how would I know that it's failed?
2. If a disk fails, will my PC continue to work as normal as far as the operator is concerned or will it see that the RAID configuration is broken when booting and refuse to boot up (which kind of defeats the point of RAID1)?
3. If a disk fails, and I remove that disk, do I have to replace it with another similar disk right away, or will the PC work with only one disk in place?
4. Somewhere I read that you can have problems when cloning Windows as the boot files have to be on a separate disk (not quite sure what that meant)? But anyway, if I clone an image my installation onto a portable drive so that I have an off-site image backed up, how would I go about restoring that image if my PC ever died, got stolen, I upgraded my disks to SSD etc? Would I need to clone the image onto another RAID1 configuration, or would it work just as happily on a single SSD or my two disks in RAID0? Are all parts of each disk (including boot sector) on a RAID1 configuration identical, or are there any special considerations when making an image for backup purposes?

I have no idea what kind of RAID1 I'm using, I assume it's on my motherboard since I must configure RAID in the BIOS before installing the operating system, but I don't know if that's a hardwarde or a software RAID if that makes any difference.

Thanks for any advice offered!

 

[Karnor00]

Raid 1 and Raid 0 are very different things.

Raid 0 effectively spreads the data evenly across both HDDs. It will look like you have a 2TB HDD, but because it can read off both HDD's at once, it should access data a bit faster. The main downside is that if one HDD fails, you will likely lose all the data.

Raid 1 mirrors data on both drives. So it looks like you have a single 1TB HDD which operates at normal speeds. The benefit is that if one HDD fails, you will still have all of your data safe on the other HDD. You should get an error message if one HDD fails and still be able to operate properly on the remaining HDD (albeit no longer having a backup).

One thing to bear in mind about Raid 1 is that it is no substitute for proper backups - there are many reasons why both HDDs could fail at the same time, which would mean no recovery (e.g. your PC being in a fire, being dropped, etc is likely to similarly effect both HDDs, and viruses would affect both HDDs).

 

[MartynB]

My experience with my old Dell machine is that the RAID flags up as degraded and the PC still functions as normal. If you replace the defective drive the PC re-builds the data from the good drive to the new drive thereby restoring the RAID 1 to normal.

Only issue is that if you put a larger drive in the RAID re-build will only match the existing size.

I found this invaluable.

 

[mishra]

Anyway, I'm wondering whether to continue RAID1 or revert to RAID0 and have a few questions that I'd appreciate advice with.

For peace of mind use RAID 1. With RAID 0 setup you are twice as likely to loose all data (regardles which drives fails). So that is why RAID 1 - for redundancy.

1. If I have a PCS machine running two identical disks as RAID1 and one disk packs up, how would I know that it's failed?

If it's a hardware raid (powered by Raid controller)... it will start to make a massive noise (beeeeep) to inform you if it failed. If it's a software raid, you will have a software that will tell you that. You can even configure so it will send you email as soon as it fails.

2. If a disk fails, will my PC continue to work as normal as far as the operator is concerned or will it see that the RAID configuration is broken when booting and refuse to boot up (which kind of defeats the point of RAID1)?

No when you use RAID 1 and one disk fails. Your PC will continue to work as normal, until you replace a broken disk. Obviosuly as soon as the other disk fails (before you replace the broken one) then you will loose all data. But PC in only one broken drive in RAID 1 will work just fine.

3. If a disk fails, and I remove that disk, do I have to replace it with another similar disk right away, or will the PC work with only one disk in place?

It will work fine with just one disk. It can be any disk, that is at least the same size as the broken one. You can replace a broken 300GB drive with a 500GB drive, but you will not be able to use that remaining 200GB.

4. Somewhere I read that you can have problems when cloning Windows as the boot files have to be on a separate disk (not quite sure what that meant)? But anyway, if I clone an image my installation onto a portable drive so that I have an off-site image backed up, how would I go about restoring that image if my PC ever died, got stolen, I upgraded my disks to SSD etc? Would I need to clone the image onto another RAID1 configuration, or would it work just as happily on a single SSD or my two disks in RAID0? Are all parts of each disk (including boot sector) on a RAID1 configuration identical, or are there any special considerations when making an image for backup purposes?

Hmm I reply later on this one, when I'm at home... as need to read that again... to busy here atm - you seem to ask confusing question

 

[mishra]

4. Somewhere I read that you can have problems when cloning Windows as the boot files have to be on a separate disk (not quite sure what that meant)?

Nah don't think that's the case. Hardware raid (through raid controller) or motherboard RAID (aka BIOS) is completely transparent to operating system. It makes no difference. Sometimes you have to provide the drivers during installation tho. Software RAID (aka Windows raid) .. is controlled by WIndows itself, so when cloning all should get cloned nicely anyway.

But anyway, if I clone an image my installation onto a portable drive so that I have an off-site image backed up, how would I go about restoring that image if my PC ever died, got stolen, I upgraded my disks to SSD etc?

This depends on type of RAID you currently use. As as said, RAID in essence is and should be transparent to your OS. SO if you want to recover your system you can do that on either RAID setup or single drive. Difference is Windows RAID (software raid), but I imagine you would restore your imagine into single drive and then you would add a new drive and create a RAID setup. To be honest, Windows RAID is not really a RAID. I mean you can do it that way... but it's only problems when you get a faulty drive. I'm not too familiar with Windows RAID config... so maybe other will help you better.

Are all parts of each disk (including boot sector) on a RAID1 configuration identical, or are there any special considerations when making an image for backup purposes?

It's all exactly the same, hence it's called a Mirrored setup.

I have no idea what kind of RAID1 I'm using, I assume it's on my motherboard since I must configure RAID in the BIOS before installing the operating system, but I don't know if that's a hardwarde or a software RAID if that makes any difference.

If you are setting it up in BIOS, it is a hardware raid. You should also have a tool/utility that came with your motherboard which you can install into Windows and it will give you tools to manage your RAID.

 

[mishra]

I say to keep you data secure.. go with RAID 1 always. But RAID configuration on it's own DOES NOT make your data safe! Yes, it will help if one of the drives fails (physically), but if you manage to corrupt files, or you will have a virus, etc... You will loose it all anyway. So keep drives on RAID 1 .. but at the same time, make sure you have some sort of backups running for critical files onto USB drive or so... SyncBack works great for data backup.

If you are after some proper Disaster Recovery, aka into any equipment (hardware independent) or into Virtual Environment then I can recommend StorageCraft Shadow Protect software... it's amazing piece of software, which I cannot recommend enough.

 

[Organground]

Many thanks for those replies. Sounds like I'm using a hardware RAID as it has to be configured via BIOS. I've just switched from RAID0 to RAID1, the only discernable difference is that gaming files that used to take around 80 seconds to load now take around 2-3 minutes (which was why I went for RAID0 in the first place). I do backup offsite, the question about whether to do 1 or 0 was more for peace of mind incase either harddisk went up the creek. Having just done a clean Windows install I will therefore clone my disk(s) to the current point in time knowing I can bring them back to an identical state if necessary in the future.

 

[Organground]

Hmm, running into problems today. Computer crashed but I managed to log out and reboot. To my surprise during the bootup the screen that shows the RAID1 configuration now says status is degraded; of my two disks one shows "member disk", the other, "error occurred". The PC boots up into Windows fine.

So it sounds like I will have to rebuild the RAID1 array. But how do I do that? The only options in the BIOS on the Intel Matrix thingy are 1. create RAID1, 2. delete RAID1, 3. return to non-RAID or 4. exit. I don't see a rebuild RAID option anywhere.

Incidentally elsewhere I've seen people referring to an Intel Storage RAID program in Windows - not installed on my machine, and I can't work out if I should even install it, as my machine is already configured to RAID1 in the BIOS, not in Windows. Motherboard is Asus P6X58DE if that helps.

 

[mishra]

So it sounds like I will have to rebuild the RAID1 array. But how do I do that? The only options in the BIOS on the Intel Matrix thingy are 1. create RAID1, 2. delete RAID1, 3. return to non-RAID or 4. exit. I don't see a rebuild RAID option anywhere.

Incidentally elsewhere I've seen people referring to an Intel Storage RAID program in Windows - not installed on my machine, and I can't work out if I should even install it, as my machine is already configured to RAID1 in the BIOS, not in Windows. Motherboard is Asus P6X58DE if that helps.

One of the drives has been marked as a faulty or incorrect. As you have noticed it doesn't stop PC from booting. Each RAID controller is slightly different. But the principle is the same. Replace broken disk with a new drive and the Raid will rebuilt itself. Sometimes you have to activate the disk, just to let RAID know you want that drive to be part of your Raid array.

I think where you might have gone wrong is by simply switching from RAID 0 to RAID 1. But all is not lost. As far as I know, you need to make that "error occured" somehow ready... as I'm sure it's a correct drive. And as soon as you do it, it will start rebuilding the array into RAID 1. During this process your PC will be slightly slow. You can restart your PC at any time during this process.

That software to control BIOS raid, should be on your motherboard CD disk. Just install it, and from Windows you will be able to see progress of the rebuilt process. Once it's ready it will say most likely RAID 1: Optimal or so.

It's hard to say... your problem is basically, the other drive that need to be member of the RAID 1 is detected as "error ocured". Maybe disconnect it from system, restart your PC, the shutdown, and reconnect .. rinse and repeat.

Before you do any changes!!!!!!!!!!!!!!!!!! MAKE SURE YOU HAVE ALL DATA BACKED UP! sorry for shouting, but seen people messing with raid arrays without having backups

If you are really struggling with this, you may take that "error occured" drive out, connect it to a different PC, and reformat it. So it's just empty space... then when you put it back to your PC, it should start revbuilding process on it's own.

 

[Organground]

Thanks for the advice.

Normally when a RAID1 goes AWOl there is a disk problem so you replace the disk with a brand new disk. I'm pretty confident in this case that the disk with the error is fine and doesn't need throwing out, but I can't see any way to rebuild the RAID array from within BIOS settings (at least, not without deleting and recreating the RAID array, which would mean completely wiping everything and reinstalling Windows - there's got to be a better way surely)?.

Please can you advise me which software from the P6X58DE CD or indeed from the Asus website) I should install to control BIOS RAID, since there are literaly dozens of things on the disk, and very little to tell me what they all do? There is one marked "Intel matrix" or something which I clicked on, but it looked like that was to create a RAID array on an additional disk (the disks that were highlighted were the memory stick sockets - the C drive didn't show up) so it didn't seem like that was appropriate. It sounds like there should be a way to control the Intel RAID1 configuration from within Windows, but I can't see any Intel software in the installed programs, and I didn't install anything from the motherboard CDROM.

 

[Organground]

Just to clarify, I think the software I was referring to was Intel(R) Rapid Storage Technology Driver, that's the only one on the ASUS website that seems to have anything to do with RAID. But I'm confused about installing it on a machine that has two hard drives configured in RAID1, except one of the drives has an error so the RAID1 isn't working....

 

[mishra]

I'm sorry I'm not too familiar with BIOS raid setups, each manufacturer has it's own controller for it - and software to control it. There are dozens of them. I'm more familiar with physical Raid controllers. This software, you mentioned, you should be OK to go and install. It will not (or it should not) change anything by itself - you would have to accept new configuration, etc...

It should be only Windows level interface to the BIOS raid. So that you can check what is happening with RAID from Windows level, as oppose to restarting your PC and accessing it through Raid BIOS. In other words you should be OK to install it and check if it will give you more options.

ps. I'm, actually at work, can't really be on this forum now I can be available after 6pm, or whole day tomorrow if you need more help, etc...

 

[Organground]

Thanks Mishra, I did as you suggested but using the latest version from the Intel website rather than the version on the motherboard CD, which seems to be the same as the driver on the Asus website too, dating from 2009. It installed fine, identified that I had one functioning disk out of two in a RAID1 configuration, and offered to rebuild the RAID1. A couple of hours later, RAID1 is working fine, and a reboot has confirmed both disks are A1-OK. Great!

 

[mishra]

Ah great news