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What happens to RAID 1 if my Mobo dies??

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May 14, 2009 4:36:20 AM

Hi guys,
I am currently trying to work out how I am going to setup a file server for my home network.
The server I’m building isn’t going to only be a file server though. I am going to install VMware ESXi to run webservers for a testing environment.

I was originally thinking of a RAID 1 setup for ESXi + all of the operating systems. And then a separate RAID 5 for my Fileserver. But after reading this thread http://www.tomshardware.com/forum/246197-32-raid-what-k...
I have decided against RAID 5, just encase something happens to my motherboard or I am unable to rebuild a failed drive. (I am looking at using the onboard raid controller because of cost limitations)

So now I’m thinking of RAID 1 for ESXi + OS and a separate RAID 1 for my Files (I will also have another drive not in the RAID to backup my files every week.

My question is, because I am going to be using onboard RAID, I am at the mercy of my motherboard. If it fails what happens to my RAID. Can you remove a single HDD from a RAID 1 and put it in another system and will it work as though it is a regular HDD (Displaying all of my data) or will I need to replace the failed motherboard before I am able to retrieve any data?

Thanks in advance
Rod

More about : raid mobo dies

a b V Motherboard
a c 362 G Storage
May 14, 2009 8:11:51 PM

The root of the dilemma is that there is no single standard for all the details of RAID. Hence the way one controller manages an array of disks, and what data is written to them where, is different from another maker's version. Result is generally that a disk full of data placed there by a RAID controller probably cannot be read by a different controller.

One way to handle that is by using a separate RAID controller board usually in a PCI slot. You count on the idea that the board can move to a new mobo if needed. Or, even if the controller board itself crashes, you can buy another from the same manufacturer and it will work.

But if you are using RAID built into your mobo's chipset (a software controller), a crash of the mobo often sends you searching for an identical old mobo as a replacement. I know of one way to avoid that, there may be more.

I have a RAID1 array running on a machine for reliability, as in a sort of instant on-line backup that restores and runs right away. Yes, I know that is not what it does, really, but the effect is like that for the untrained user. It is on a mobo with nVidia chipsets including their built-in RAID controller. If you check out the nVidia website, you will find they claim (I have not had occasion to test this!) that ALL of their current and recent RAID systems use exactly the same algorithms, so you actually can move a set of disks run by one of their RAID systems to another machine with an nVidia chipset and built-in RAID, and it WILL be able to handle it and get all the data!

Even assuming nVidia's claims are completely accurate, you still have limits on what RAID can do. In my case with RAID1, I recognize that any operation that reads and writes data will happen to both disks, so an application that writes bad data to a file will still cause trouble. A malicious virus will cause the same trouble with RAID1 as with no RAID. What my system does is limited to protection against a failure of ONE hard drive. When that happens I still need to respond relatively quickly to the warning that pops up so the array (which will default to using only the remaining good disk) can be repaired and rebuilt. So, in addition to that RAID1 array, I have an automated daily backup system running and a less-frequent process for moving entire backups offsite.

Even RAID5, which many used to regard as almost the ultimate for servers in terms of reliability and automated recovery, can have problems. I saw a great proof of that where I worked. The main server's RAID5 array crashed. First problem was that the hardware supplier did not have a replacement drive locally and had to fly one in. That's not a RAID issue, but lots of server admins will keep at least one spare drive on site; some even keep them in a "warm state" ready to swap in on very short notice. (Now you're buying six drives (or seven?), not 5, up front to get 4 drives' worth of storage capacity.) Anyway, when the replacement drive was installed and the array rebuild operation started, they discovered that a SECOND drive in the array also had failed at the same time, and the rebuild could not be done! After the second unit was replaced, they did a complete restore from backups, and that took them nearly three days with a server in constant heavy use. It worked because the system admins had a very good backup system with daily incremental and periodic full backups, both on- and offsite. These are the incidents that push the pro's into more advanced RAID systems on servers that cannot tolerate downtime, but they are more complex and more expensive (by a lot!) than you would ever do for your home server system.
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September 26, 2009 10:10:44 PM

I cheked out the nVidia website, but I could not find their claim that ALL of their current and recent RAID systems use exactly the same algorithms! Please tell me where did you find it? (I found only your other statement on http://forums.anandtech.com/messageview.aspx?catid=27&t...)
a b V Motherboard
a c 415 G Storage
September 26, 2009 10:38:51 PM

Rod_C said:
My question is, because I am going to be using onboard RAID, I am at the mercy of my motherboard.
I wouldn't loose too much sleep over this. The reality is that your data is at the mercy of a myriad of risks, a lot of which RAID can't protect you from. Therefore, you need to make regular backups and you need to test your restore procedures. If you've done this, then the only real concern about loosing a motherboard is the downtime to replace and restore.
a b V Motherboard
a c 127 G Storage
September 27, 2009 11:15:17 AM

Any RAID is recoverable using software only (i.e. you dont need to buy a new controller or anything), if you know what you are doing. However, why use RAID1 if you have no backup anyway. Why not forget about RAID1 and use the 2 drives as backup instead? This will protect against much more dangers than RAID1 alone can ever do and it doesnt cost you anything. Any performance benefit from RAID1 is theoretical and most implementations have the performance level of a single disk during both reading and writing.
February 13, 2010 12:10:21 AM

sminlal said:
I wouldn't loose too much sleep over this. The reality is that your data is at the mercy of a myriad of risks, a lot of which RAID can't protect you from. Therefore, you need to make regular backups and you need to test your restore procedures. If you've done this, then the only real concern about loosing a motherboard is the downtime to replace and restore.


HELP!
my asus a8v-e motherboard died. I have two 300gb hard drives in raid 1 configuration.
When i put one of the drives into another computer, i can see the drive volume in the bios, but not in windows xp , disk management. is there a way to get the data from one of the drives without purchasing another identical motherboard?
a b V Motherboard
a c 415 G Storage
February 13, 2010 12:45:29 AM

I see that you're quoting my point about making backups. If you've made a backup, you just have to set your disks up on any old motherboard and then restore from the backup...
February 13, 2010 5:52:33 PM

sminlal said:
I see that you're quoting my point about making backups. If you've made a backup, you just have to set your disks up on any old motherboard and then restore from the backup...



my back up drive is not up-to date....
can you help me with getting the data off the raid 1 drives?
my asus a8v-e motherboard died. I have two 300gb hard drives in raid 1 configuration.
When i put one of the drives into another computer, i can see the drive volume in the bios, but not in windows xp , disk management. is there a way to get the data from one of the drives without purchasing another identical motherboard?
a b V Motherboard
a c 415 G Storage
February 13, 2010 6:23:35 PM

I'm sorry I can't be of more help. I've done a lot of work with RAID, but as a data center administrator the strategy that's always saved me has always been to mistrust everything and be really anal about backups. RAID is great for eliminating downtime due to drive failures, but when something else goes wrong my experience is that every RAID system has it's own peculiarities when it comes to data recovery. So I don't use RAID on my home system because it just makes adds complications I could do without (as you've just found out). Not to mention that I'm even less of an AMD expert.

I'll defer to someone else with experience using AMD motheboard-based RAID, but assuming you've been using the chipset RAID solution then I strongly suspect that if you buy another motherboard that uses the same chipset then you can probably recover the data. But the devil is in the details.

Failing that, I've seen in other posts that there are some software packages designed to recover data from failed RAID sets that can automatically recognize the RAID format and retrieve the data for you. Perhaps someone here can post a link to one or more of them...
!