A few questions about RAID 5

[mertov]

1_ If I build raid 5 with 4 2 tb disc, will I have (4-1)x 2 tb = 6 tb space?
2_ Do I have to format the pc to be able to create raid 5 array? Or adding discs from matrix storage manager is enough?
3_ Is this the best way to protect personal movie,tv series archive?
4_ Lets assume I created raid 5 with 3 disc is it easy to add another disc after?
5_ I have 1 ssd, 1 tb, and 2 2tb disc, one of the 2 tb discs is full the other one is empty, Before I create raid 5 do I have to move my all data or only my data on 2 tb discs?
6_ Do I need a raid card for raid 5?
7_ What is the difference betwen software raid and hardware raid?
System spec.
i5 3570k @4.5
Asrock extreme4

 

[Super XP]

And quote from Yahoo Answers from wiki info. Regarding 4 Drives.

Raid 5 is much more faster than regular hard driver , and much more reliable , but it reduces the capacity by 38%
you'll be able to use 62% of total hard driver

Raid 5 is a Striped set with distributed parity or interleave parity. Distributed parity requires all drives but one to be present to operate; drive failure requires replacement, but the array is not destroyed by a single drive failure. Upon drive failure, any subsequent reads can be calculated from the distributed parity such that the drive failure is masked from the end user. The array will have data loss in the event of a second drive failure and is vulnerable until the data that was on the failed drive is rebuilt onto a replacement drive.

http://answers.yahoo.com/question/index?qid=20090102043809AAWicJw

In regards to question 5, yes you need to back up your data on another drive that will not be in the Raid. Everything will be wiped during the RAID 5 setup.

 

[repman244]

3. RAID is for redundancy not for backups (it helps you if a drive fails but it doesn't save you if you delete data on it).
6. For RAID 5 I would say yes (if you need the best performance). It will operate much faster with a hardware RAID card.

Also note that RAID 5 is good for reading data but is slower for writing (compared to something like RAID 0).

 

[mertov]

3. RAID is for redundancy not for backups (it helps you if a drive fails but it doesn't save you if you delete data on it).
6. For RAID 5 I would say yes (if you need the best performance). It will operate much faster with a hardware RAID card.

Also note that RAID 5 is good for reading data but is slower for writing (compared to something like RAID 0).

I do not need performance since my os installed on ssd so without raid card I would be able to create raid 5 right? Because my mobo supports raid 0,1,5,10

 

[repman244]

I do not need performance since my os installed on ssd so without raid card I would be able to create raid 5 right? Because my mobo supports raid 0,1,5,10

Yeah, if the motherboard supports it then it should work.

 

[Super XP]

Use all 4 drives for RAID 5, just be sure you know which is which pending a single drive failure.

 

[mertov]

Use all 4 drives for RAID 5, just be sure you know which is which pending a single drive failure.

You mean 4 2 tb disc by saying use all 4 drives don't you? I have never built raid even raid 0 so I have no idea how to do it. The info about raid 5 on the web is so old.

 

[Law-II]

The info about raid 5 on the web is so old.

Hi

have to assume your asrock mobo is based on a z77 [as this is not mentioned in the OP]; look here for raid instalation guide - http://www.asrock.com/mb/Intel/Z77 Extreme4/?cat=Manual

Note: you will need the CD that came with your mobo for reference

atb (all the best)

Law-II

 

[Super XP]

You mean 4 2 tb disc by saying use all 4 drives don't you? I have never built raid even raid 0 so I have no idea how to do it. The info about raid 5 on the web is so old.

I've built many RAID 0's and always everything gets wiped on them. The only issue was one drive failed and I lost everything going. But I always backed up my info. So I was OK.

 

[Wrigleyvillain]

RAID 5 is not really a good option for a "high performance" desktop machine. Also, it dedicates one drive to "parity" for a rebuild if one dies so in this case you would have 4TB space.

And, NO, it is not "the best" way to protect this data. Not even close. RAID is not a "backup" it just allows people, usually in enterprises, to get back up and running quicker if a drive dies (as opposed to having to restore everything from tape or whatever).

In your case I would first get a real backup scheme in place and then maybe run RAID 1 which mirrors an exact copy of one drive to another in real time. RAID 10 stripes a RAID 1 array into RAID 0 (so it's like RAID 1 + 0 and they call it "ten" and uses 4 drives) but the Intel controller does not support reading from all four at once so performance is not where it could be, unfortunately. Or maybe it was writing to all four. At any rate, I was disappointed in the performance and Googled it and learned this.

 

[mertov]

Hi

have to assume your asrock mobo is based on a z77 [as this is not mentioned in the OP]; look here for raid instalation guide - http://www.asrock.com/mb/Intel/Z77 Extreme4/?cat=Manual

Note: you will need the CD that came with your mobo for reference

atb (all the best)

Law-II

Thank you so much I will follow instructions that you have sent. I didn't now that kind of gudie exist on Asrock website.

 

[Filiprino]

You can do two RAID5. One were you work on and the other one maintains a backup of the first one.

 

[mertov]

RAID 5 is not really a good option for a "high performance" desktop machine. Also, it dedicates one drive to "parity" for a rebuild if one dies so in this case you would have 4TB space.

And, NO, it is not "the best" way to protect this data. Not even close. RAID is not a "backup" it just allows people, usually in enterprises, to get back up and running quicker if a drive dies (as opposed to having to restore everything from tape or whatever).

In your case I would first get a real backup scheme in place and then maybe run RAID 1 which mirrors an exact copy of one drive to another in real time. RAID 10 stripes a RAID 1 array into RAID 0 (so it's like RAID 1 + 0 and they call it "ten" and uses 4 drives) but the Intel controller does not support reading from all four at once so performance is not where it could be, unfortunately. Or maybe it was writing to all four. At any rate, I was disappointed in the performance and Googled it and learned this.

I have a 120 gb vertex 3 ssd so I am looking performance for my secondary storage.To be honest I still do not understand how this raid 5 exactly works. Lets say I built raid 5 with 3 2 tb discs and filled them totally in this case I will have 4 tb data and if one drive fails will I be able to get my all data on the failed disc? Or will I able to get my half data on the failed disc.
Last question is did you ever add a disc after building raid 5?

 

[Wrigleyvillain]

Well tbh I messed around with RAID 0 in the past but am just getting into all this now as I have dedicated to my P55 rig to a home server. Am just running my first RAID 5 array for testing essentially as of last week. I have not yet added a drive but am thinking about removing one/simulating a failure to test rebuilds. Frankly, I do not understand exactly how any drive can die and it rebuilds due to my understanding that just one of the three is dedicated to the "parity" data so I guess I need to read more about it. Intel Rapid Storage Technology package documentation and help has more info.

Thank you so much I will follow instructions that you have sent. I didn't now that kind of gudie exist on Asrock website.

Ya that may be from Intel.

 

[Mindweaver]

I would not setup a software raid 5... I would only setup RAID 0 or 1.. 0 for speed and 1 for redundancy.. You can try RAID 10.. It's RAID 1 and RAID 0 together 1+0... It just costs half your space...

If you lose power you have the chance of losing your RAID 5 configuration.. Which sucks, because you could lose everything. I would only recommend RAID 5 with a Hardware RAID card with a battery backup on the card (BBU) Battery Backup Unit. Plus, using software will kill your CPU performance. I've had Hardware RAID 5 setups with out a BBU to lose the configuration and that sucks ass. Just my two cents.

EDIT: Using RAID 5 I would use 4 drives and remember adding to many drives to a RAID 5 can hurt performance, but 4 drives have always performed well.

 

[FordGT90Concept]

1_ If I build raid 5 with 4 2 tb disc, will I have (4-1)x 2 tb = 6 tb space?
2_ Do I have to format the pc to be able to create raid 5 array? Or adding discs from matrix storage manager is enough?
3_ Is this the best way to protect personal movie,tv series archive?
4_ Lets assume I created raid 5 with 3 disc is it easy to add another disc after?
5_ I have 1 ssd, 1 tb, and 2 2tb disc, one of the 2 tb discs is full the other one is empty, Before I create raid 5 do I have to move my all data or only my data on 2 tb discs?
6_ Do I need a raid card for raid 5?
7_ What is the difference betwen software raid and hardware raid?
System spec.
i5 3570k @4.5
Asrock extreme4

1. Yes.
2. The disks will have to be formatted when the RAID array is created. I think it can spare all disks not being added to the RAID array but back up everything just in case a mistake is made.
3. A backup is better (e.g. external drive in a lock box). RAID5 will only protect the data from a single hard drive failure at a time.
4. No, unless it is a hot-spare where it only takes the place of a defective drive. Parity information has to be recalculated for all the drives in order to add more to the array. The controller might be able to do it without formatting--check documentation.
5. Nothing can be on the disks you intend to RAID. All disks will be wiped when the RAID is created.
6. No, if your motherboard controller supports it.
7. Software is software (often Windows copying data to separate hard drives without the disk controller knowing they are RAIDed), hardware is hardware (software doesn't even know the volume is a RAID withought digging through drivers for it). If it isn't hardware RAID, it isn't worth doing.

 

[repman244]

I still do not understand how this raid 5 exactly works. Lets say I built raid 5 with 3 2 tb discs and filled them totally in this case I will have 4 tb data and if one drive fails will I be able to get my all data on the failed disc? Or will I able to get my half data on the failed disc.

I hope this will help:

If one drive fails you don't loose any data because the data that was on the failed drive is spread on the other drives.
So when you replace the failed drive your RAID 5 array will automatically rebuilt.

7_ What is the difference betwen software raid and hardware raid?

With a hardware RAID controller card you have a dedicated CPU on that board for handling the RAID. It's much faster than the software RAID that comes with the motherboard.

 

[Disparia]

Hardware is nice if the situation calls for it, but I agree with Intel that those situations are becoming fewer and fewer:

"I'll plead guilty. We stood up here 10 years ago and told you software RAID sucked, you didn't want it, it wasn't a viable solution," Susan Bobholz of Intel's storage product marketing group told attendees at a Wednesday SAS and RAID session at the Intel Developer Forum in San Francisco.

"But that's one of those things that's starting to change in the industry," she added. "Software RAID is no longer the evil stepchild of the enterprise anymore."

Citing testing done by Tom's Hardware, Bobholz claimed that "Software RAID equals or outperforms hardware RAID these days. And this is because the host processors have gotten so much faster and you've got all the different cores going on."

Referring to software-RAID I/O performance of years past, she said: "Historically, it was slower. It just was. And it's not anymore. And in fact in a lot of cases it's a higher-performing solution."

To be fair they are talking about 4/8-port controller on Patsburg chipsets (X79, C600), but they're also talking about workstation and server applications. For the consumer, Intel hit their stride starting with the ICH9R in my opinion.

Generation vs generation, AMD chipsets do perform less than their counterparts. My array which did 400MB/s on ICH10R does around 250MB/s on SB950. Since it's just storage, not really noticeable.


As everyone else has said, if you do go ahead with RAID-5 you'll still want to backup anything that can you absolutely can't lose.

 

[mertov]

I would not setup a software raid 5... I would only setup RAID 0 or 1.. 0 for speed and 1 for redundancy.. You can try RAID 10.. It's RAID 1 and RAID 0 together 1+0... It just costs half your space...

If you lose power you have the chance of losing your RAID 5 configuration.. Which sucks, because you could lose everything. I would only recommend RAID 5 with a Hardware RAID card with a battery backup on the card (BBU) Battery Backup Unit. Plus, using software will kill your CPU performance. I've had Hardware RAID 5 setups with out a BBU to lose the configuration and that sucks ass. Just my two cents.

EDIT: Using RAID 5 I would use 4 drives and remember adding to many drives to a RAID 5 can hurt performance, but 4 drives have always performed well.

Are you sure about loosing everything? Because the city that I live still has power cut problem even though it is capital and I thought raid 5 would give me a chance to recollect my data if anything bad happens. I knew only raid 0 has loosing all data risk.

 

[mertov]

1. Yes.
2. The disks will have to be formatted when the RAID array is created. I think it can spare all disks not being added to the RAID array but back up everything just in case a mistake is made.
3. A backup is better (e.g. external drive in a lock box). RAID5 will only protect the data from a single hard drive failure at a time.
4. No, unless it is a hot-spare where it only takes the place of a defective drive. Parity information has to be recalculated for all the drives in order to add more to the array. The controller might be able to do it without formatting--check documentation.
5. Nothing can be on the disks you intend to RAID. All disks will be wiped when the RAID is created.
6. No, if your motherboard controller supports it.
7. Software is software (often Windows copying data to separate hard drives without the disk controller knowing they are RAIDed), hardware is hardware (software doesn't even know the volume is a RAID withought digging through drivers for it). If it isn't hardware RAID, it isn't worth doing.

Thank you so much Is there any risk loosing all data on raid 5 due to power cut etc?

 

[FordGT90Concept]

That's always a risk. A UPS is usually a good investment.

 

[mertov]

I hope this will help:

http://blog.everycity.co.uk/wp-content/uploads/2008/10/raid5.png

If one drive fails you don't loose any data because the data that was on the failed drive is spread on the other drives.
So when you replace the failed drive your RAID 5 array will automatically rebuilt.



With a hardware RAID controller card you have a dedicated CPU on that board for handling the RAID. It's much faster than the software RAID that comes with the motherboard.

I have seen that picture but I still do not understand how I do not loose any data. Lets say 3 same discs on a raid 5 array and the the raid 5 array is totally full. If one drive fails I should be able to get half of the data from the failed disc. If raid 5 had total data security no none would ever built raid 1 in my opinion

 

[FordGT90Concept]

When a drive fails, it uses the parity information on the other drives to rebuild the data on the failed drive. This process takes hours to complete but, so long as nothing happens to the other drives in the meantime, no data is lost.

 

[repman244]

I have seen that picture but I still do not understand how I do not loose any data. Lets say 3 same discs on a raid 5 array and the the raid 5 array is totally full. If one drive fails I should be able to get half of the data from the failed disc. If raid 5 had total data security no none would ever built raid 1 in my opinion

One of the advantages is that RAID 5 allows more space used (RAID 1 is total space split in half) and also allow faster reads (with the same number of disks) but has lower writes.

If you have 4 drives in RAID 5 each drive is split into 3 blocks + parity block (the reason behind loosing some space).
The parity, like FordGT90Concept has the information to rebuild the disk...so instead of "backing up" on one drive (like RAID 1), the "backup" is spread across all of the disks.

Hope I got it right

 

[Wrigleyvillain]

The Intel onboard is better than straight-up software RAID like madm in linux or whatever and is usually referred to as "Fake RAID". But no it's nowhere as good as a higher end dedicated controller from, like, LSI.

The most affordable good SATA/SAS RAID controller right now is the IBM M1015 a rebranded LSI that you can get on ebay for $65. But it requires a $100 add-in chip to do RAID 5 (0, 1 and 10 without). Old Dell Perc 5's aren't bad either.

Interestingly enough timing-wise, I decided to switch some ports around and my test RAID 5 array has to rebuild now. For some reason I only see activity on one of the three disks though. Maybe this is different than having to rebuild a new clean one though. Guess that makes sense. Though not sure exactly what it's doing. Yeah it will take like 10 hours too. 1.4TB array.