View Full Version : Raid
My motherboard supports
"RAID 0(Data Striping), RAID 1(Data Mirroring), RAID (0+1) and also JBOD function, delivering both data protection and data fetching performance to meet intensive applications demands."(taken from the site.) now i get raid 0 and raid 1 but what is raid 0+1? what are the performace differences between 0+1,0, and1? i know 0 is faster than 1, but i want the security features of raid 1. is 0+1 faster or slower than RAID 1? and i need two drives to do this, i know that much, but in the bios how do i set it to these different types of RAIDs?
deathman20
10-27-03, 11:36 AM
Well think of raid 0+1 as a combination of Raid 0 and Raid 1. It does both if I can remember correctly. You would need 4 drives to do this.
So for example drives 1&2 are in a raid 0 setup, but with Raid0+1 drives 3&4 are in a Raid 0 setup too just mirroring drives 1&2. So you can take this 1 of 2 ways. Its Raid 0 with a mirror, or its a Raid 1 with a nice bump up in writing throughput.
Edit: WOOT Finally a 1 to 1 post ratio. Shows what happens when I get away from the OC'ing forums I lose my posting per day standing.
wow thanks for the quick reply and umm i need 4 drives to do RAID 0+1? i thought at the sticky at the top it only said 2.... but maybe cause i don't get what im reading.... ok.... now how do i change the raid in the bios? and the writing for Raid 1 is slower, but how much slower? is the increased speed of the reading worth the slower writing speed?
another question.... how can i find what kind of sata raid i have? i don't see it on the site. does sata raid work the same way?
deathman20
10-27-03, 11:56 AM
http://www.raidweb.com/whatis.html
This link at the bottom has what the raid setups need for drive wise, and it is 4 for 0+1. Thought I was right.
As for Raid 1 here. Writing should be as fast as the slowest drive if not mistaken. This was taken right from the site above.
RAID 1: Known as "Disk Mirroring" provides redundancy by writing twice - once to each drive. If one drive fails, the other contains an exact duplicate of the data and the RAID can switch to using the mirror drive with no lapse in user accessibility. The disadvantages of mirroring are no improvement in data access speed, and higher cost, since twice the number of drives is required. However, it provides the best protection of data since the array management software will simply direct all application requests to the surviving disk members when a member of disk fails.
As for how its setup in the BIOS, you'd be asking the wrong person :). I only did raid once and had a problem with it. Right now I'm in the process of thinking about another raid setup but I'm waiting on how the new Raptor drives turn out for preformance before I choose to go raid with those right now or just get 1 to start with.
deathman20
10-27-03, 11:58 AM
Oh and your other question, SATA if not mistaken works the same wait ATA raid works. So there should be any problem with that. The Raid setup window should appear right after the bios screen when booting.
why is RAID 1 more expensive? and the reading speed is fast right? thats all i need. is it as fast reading as RAID 0?
I guess mirroring is more expensive in terms of cost per megabyte, as you only get half of the total capacity of the 2 drives.
with regular bunch of disks or striping, you will have the entire capacity of the drives.
read might be somewhat faster than a single disk, not sure by how much though. might be slower than striping though.
deathman20
10-27-03, 12:59 PM
Raid 1 is more expensive because that it uses 4 drives. Besides using the 4 drives say your using 80 gig drives. In raid 0 setup you would have a nice 360 gig array. Yet no data security. With raid 0+1 you'd only have 180 gig array the speed of raid 0 (probley a bit slower due to mirroring) and the security of raid 1 if a drive fails.
Like what I said before about speed is that its totally a ?? unless someone here runs a raid 0+1 array to give us some stats.
deathman20
10-27-03, 01:19 PM
Guess if your controller supports a Raid 5 setup I'd choose that over a Raid 0+1 setup. It only takes 3 disks to set up and it has security and also better transfer rates compared to a Raid 0+1 setup.
Stan, the SATA raid controller on you mobo only support a 2 drive raid array. That means you can't use a 0+1 array. If you want to have a 0+1 you'll have to use the PATA raid controller on your mobo or buy a SATA controller card that supports 0+1
deathman20
10-27-03, 01:57 PM
Oops didn't think of that one :) Good call pkrew
ok, well im looking to set up raid with the ata first anyway cause i really only need one raid array... maybe when i get more money ill get the sata raided also.... my ata raid can support 4 drives right? but it cant do raid 5 unfortunately. so what is the difference in read performance between raid 0 and raid 1? i really only want 2 drives, cause it would be a waste of money to get a third
Yes, your ata raid will support 4 drives. I don't really know the difference, but I suspect that the raid 1 would perform similar to a single drive and perhaps slower.
but it will read about the same speed as a raid 0 right?
deathman20
10-27-03, 08:24 PM
In therory it should read the same speed as Raid 0, but I'm not 100% sure on that one.
hmmm... sorry to say this, but it looks like mirroring is a lot slower than striping, and does not seem much faster than 1 single drive...
here's a detailed report on RAID performance:
http://www.tech-report.com/reviews/2002q4/ideraid/index.x?pg=10
Nice link Shiyan. Very informative
which one of those graphs is for the read time only? or is that what they are?
EDIT: http://www.acnc.com/04_01_01.html
it says that RAID 1 writes that same speed as one drive, but reads twice as fast... that would be what im looking for, but does the linky shiyan posted disprove that?
that is what it suggests, but I'm not sure how accurate that is.
I say this because if you look at the graphs for transfer rates at the beginning and end, Raid 1 (mirroring) is significantly slower than Raid 0 (striping), pretty much the same as using just 1 drive.
begin: http://www.tech-report.com/reviews/2002q4/ideraid/winbench-begin.gif
end: http://www.tech-report.com/reviews/2002q4/ideraid/winbench-end.gif
This would make sense, because although there are 2 drives to read from, the length of track on each platter used up to write one file in a mirror array is still going to be the same as that in a regular 1 disk setup, whereas the track length in the striped array with 2 disks would be just half, due to only half the data being sent to each drive. And as the drives are still spinning at 7200 rpms, the time to read the track for the file in the mirror array won't be much different from that of the single drive.
That's just what my interpretation is for what you see in those graphs.
darn... so then there really is no point in running raid 1 huh? it just like running two drives seperate....
and another question for raid is i have 2 120 gigs it would just show up as 1 240.... right?
the only point for raid 1 (mirroring) is not performance, but security.
if one drive fails, and the other drive is still alive, then you still have your data.
mirroring really does do what the name suggests. it just writes the system data twice, once on each disk, at the same time, so that if you removed one disk from the array, you could just run it off an IDE controller, and never know it was on a RAID controller.
and in raid 1 (mirroring), if you use 2 disks of equal size, say 120GB each, you'll only see 120GB of available space under windows. This is half of the total capacity of the 2 drives.
in raid 0 (striping), you can use 2 disks or more. You nearly double your transfer rate with 2 disks, and increase it even more with more disks, but the gains diminish the more disks you add. You still keep the total capacity of the drives, so 2x 120GB in striping is 240GB. but, if one drive fails, you loose ALL the data.
raid level 5 offers security and speed, but requires several disks. with severall disks, it basically stripes the system data + parity data to all the drives, and if one drive fails, the data on that drive can be rebuilt from the parity data from all the other drives. Losing 2 disks at the same time leads to the loss of all data. The available space is equal to (number of drives - 1) x size of smallest disk. You need at least 3 drives for this setup.
another possibility is level 1+0, basically a mirror array made up of 2 striped arrays. You need at least 4 drives for this kind of setup. Your storage capacity will be half of the total capacity of all your drives--------------------------------------------------------------------------
with your controller, you wrote that you have the options of 0, 1, or 0+1, so if you only have 2 disks of 120GB, then the only options are level 0 for speed (with capacity of 240GB), or level 1 for security (with capacity of 120GB).
If you want to use 0+1, you'll need to get 2 more drives, so you have 4 in total. if you have 4x 120GB drives, then you'll have 240GB of space with level 0+1. (are you sure this is supported though?)
Or you could just run them off the controller but as single drives.
deathman20
10-28-03, 10:59 AM
Raid has many options for choice. Really the only feasible ones are:
Raid 0: Just for the pure speed and snappiness of it
Raid 1: Slow but for data security reasons
Raid 0+1: Lots of drives but the speed and security of Raid 0 and Raid 1
Raid 5: The speed and security of Raid 0 and Raid 1 but with less space lost due to mirroring. You need 3 drives but you only loose say 120gb's if you have 3 120 drives in this config. Still if 1 drive fails it will operate as normal.
deathman20
10-28-03, 11:00 AM
Doh Shiyan you beat me to the punch, dang work has to bug me when I write here hehehe.
Originally posted by shiyan
the only point for raid 1 (mirroring) is not performance, but security.
if one drive fails, and the other drive is still alive, then you still have your data.
mirroring really does do what the name suggests. it just writes the system data twice, once on each disk, at the same time, so that if you removed one disk from the array, you could just run it off an IDE controller, and never know it was on a RAID controller.
and in raid 1 (mirroring), if you use 2 disks of equal size, say 120GB each, you'll only see 120GB of available space under windows. This is half of the total capacity of the 2 drives.
in raid 0 (striping), you can use 2 disks or more. You nearly double your transfer rate with 2 disks, and increase it even more with more disks, but the gains diminish the more disks you add. You still keep the total capacity of the drives, so 2x 120GB in striping is 240GB. but, if one drive fails, you loose ALL the data.
raid level 5 offers security and speed, but requires several disks. with severall disks, it basically stripes the system data + parity data to all the drives, and if one drive fails, the data on that drive can be rebuilt from the parity data from all the other drives. Losing 2 disks a the same time leads to the loss of all data. The available space is equal to (number of drives - 1) x size of smallest disk. You need at least 3 drives for this setup.
another possibility is level 1+0 (also known as level 10), basically a mirror array made up of 2 striped arrays. You need at least 4 drives for this kind of setup.
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with your controller, you wrote that you have the options of 0, 1, or 0+1, so if you only have 2 disks of 120GB, then the only options are level 0 for speed (with capacity of 240GB), or level 1 for security (with capacity of 120GB).
If you want to use 0+1, you'll need to get 2 more drives, so you have 4 in total. if you have 4x 120GB drives, then you'll have 240GB of space with level 0+1. (are you sure this is supported though?)
Or you could just run them off the controller but as single drives.
ok maybe ill just to RAID 0 then... Yes im sure my mobo does 0+1 cause that was copied from thier website... but i don't want to buy 3 more drives. i wish i could do RAID 3....:( also raid 0+1 is not raid 10.... if i do 0+1 when one disk fails the RAID will just become RAID 0.. i don't quite get it. http://www.acnc.com/04_01_0p1.html RAID 0+1 is NOT to be confused with RAID 10.
what are the chances of drives failing? is there a warning so i can know when the drive is about to fail? or maybe ill do RAID 0 and have one of those massssive Maxtor backup drives.... can i have some opinions on what to do? cause i think my computer is significantely fast and i think its my harddrives that are the bottleneck of the computer. i might ask for another harddrive for christmas so im asking all about this now... and please don't recommend a controler card unless is absolutely necessary because i don't have any slots in the back of my computer open.... i guess i could take out one of the usb things, but only if there is a much better RAID that my motherboard cannot do.
link to motherboard: http://www.giga-byte.com/MotherBoard/Products/Products_GA-8KNXP.htm (mine is not the revision 2)
also what is JBOD ?
didn't know that 0+1 was different from 10. my bad. thanks for the heads up.
what they mean is that if one of the disks in a 4 disk raid 0+1 array setup dies on you, one of the two striped arrays dies. Remember that the mirrored array is made up of the 2 striped arrays. Because 1 is now dead, you are left with just 1 working striped array.
Then you are just left with a mirror array with just one member left, the level 0 raid array. This is why when one disk dies in a 0+1 array, you are left with a level 0 array.
Chances of a drive failing... above my head. Although I remember that there were some good FAQs over at storagereview.com I'll try to find the right one for you.
enabling SMART can help with predicting drive failure, but isn't a guarantee.
backing up is always a good idea. backing one of thos huge 5400rpm disks could be quite a good solution.
JBOD: Just a Bunch Of Disks (at least that's what I remember...)
Deathknight
10-28-03, 04:36 PM
Originally posted by stan03
darn... so then there really is no point in running raid 1 huh? it just like running two drives seperate....
Well if its performance you are looking for then raid 1 is not what you want. I sleep better at night knowing that my most important data is stored on my raid 1 box though.
i think ill do RAID 0 with one of those massive Maxtor external backup drives.... does that sound good?
doodah10
10-28-03, 10:13 PM
RAID 1 is just 2 drives with the same content. If your worried about a drive dieing, that would be a reason to use 1. I have two PCs with RAID 0 using IBM 120GXP on one and Maxtor SATAs on the other. Never a problem with either. If one of your RAID 1 drives has a virus, they both do. Not so secure. I think your best solution is what I've been using. That is a third HD on the IDE controler for backup. Every so often check the RAID 0 array for viruses then ghost the RAID drives to the single HD. Or create or buy a script that will back up your My Documents and Program Files at the same time every day, to the IDE drive. If the array dies, just set your BIOS to boot from the IDE drive and your still in business. I believe this is essentially what RAID 5 does.
stan03: that sounds good. :thup:
doodah10: that's a good setup, but raid 5 is a little different from what you described, this is what I wrote a little higher up in this thread:
"raid level 5 offers security and speed, but requires several disks. with severall disks, it basically stripes the system data + parity data to all the drives, and if one drive fails, the data on that drive can be rebuilt from the parity data from all the other drives. Losing 2 disks at the same time leads to the loss of all data. The available space is equal to (number of drives - 1) x size of smallest disk. You need at least 3 drives for this setup."
yea well i already have an sata drive... but im not sure how im gonna use it when i get ata 133 raid.... maybe ill just use the sata as storage.... and then have like a 300 gig as backup....
and ummm whats ghosting?
ghosting, as in making an image of your entire disk or partition using the program Norton Ghost.
you can also use Disk Image from Powerquest to make an image of your drive.
a disk image is like a snapshot of your system. when you restore the disk image, it overwrites everything, restoring the system to exactly like when you made that disk image.
ok... what about those harddrives with the "one button backup" or something like that.... or am i confusing something wiht something else?
I'm not familiar with those hard disks... sorry.
disk imaging is a good way to backup, but not always very practical, as you need to get out of windows to do it.
scheduling windows to make a back up every day is more practical.
the best would probably to do a mix of the two methods.
deathman20
10-29-03, 10:45 AM
Yea I know the type of drives your talking about Stan, well at least 1 type of that. At work I had an HP backup type system where it backedup all data on the computer everytime you started the computer.
It does make a total copy of everything on the computer and it can be restored pretty easy but there is compatibility issues due to OS's. This was done in real time in windows.
There is 1 program that I've heard that can actually make a drive image in windows. Of course I don't remember it but it was talked about within the last week here in this section.
nice! that's real handy. I'd like to have something like that.
wait ghost doesn't work though windows?
deathman20
10-29-03, 11:31 AM
I used ghost recently and had to use it through dos. That was the ghost with Norton System Works 2003. Love that program has lots of goodies in there for helping to fix the system.
yea i have system works 2003... got it for 5 bucks :D so i have to use dos... maybe the maxtor with the one button thing will work... now just got to wait till christmas....
in regaurd to your other thread.... i want those 74 gig raptors :D
I think you can run a disk imaging program from within windows, but not to image the partition that windows is running on.
and I'd like a Raptor 73GB too! :D
deathman20
10-29-03, 11:59 AM
Oks since you all want the Raptor, why don't yea buy me a couple test samples then I can make a report on it :D
ummmm same here..... deathman20 does tests on the B type cpus and ill do it with the C type chips :D lol
EDIT: OMG the one touch backup drives cost like 400 dollars:eek: :eek: :eek: , man for that money id just get 3 more drives and do 0+1..... grrrrr thats annoying.... maybe ill just do RAID 0.... are there warnings before a drive fails?
sometimes SMART can pick it up, or if you start getting bad sectors, but often you don't, and they die on you.
I've had just 1 drive die on me so far, a deathstar. although another deathstar might have just died, according to my father.
deathman20
10-29-03, 09:49 PM
Well no warning signs really. One min it could be fine the next it could be crocked over dead and your going "wtf?"
dang.... maybe ill use the sata drive to store my documents.... how should i use my drives? i know i should put the OS and games on the RAIDed drives but what else? how do you have it set up?
I think one possibility is to set up a RAID 0 array for speed, keep everything on there if you have enough space, and then use your single drive to make daily backups of all your important stuff.
yea ill have 240 gigs of space.... thats plenty for me:D and for daily backups is there a program you recommend, or should i just use windows explorer?
deathman20
10-30-03, 12:43 PM
Copy and paste :) Best way to do it expecially if you know what your working with. Like text docs for school, resumes, saved games, 3d work, pictures, webpages. All that you know when you start working on it. So you can just make a quick backup of it right when your done with it.
As for a program that would do something like this. No clue at all how this works but if not mistaken windows has a sycronization option in it that can backup directories and such. Not sure how it all works but its an option that you might want to look into.
there is that backup utility as well...
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