Can you stripe together 2 striped sets?

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Originally posted by vertices
Wouldn't another logical "cheap" method here be to just set up all 4 disks as independent disks on the hardware raid controller and then just RAID 5 them through Windows Server?

You would still get speed enhancements, but better yet, if one drive goes down you don't lose everything.

Thats what I would do in that situation.:)

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Your system would be quite slow. Software RAID is a very big burden on the CPU. Not only that, you must also have a basic volume from which to boot because dynamic volumes are not bootable.

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Originally posted by ua549
Your system would be quite slow. Software RAID is a very big burden on the CPU. Not only that, you must also have a basic volume from which to boot because dynamic volumes are not bootable.

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yeah this was broght up in another forum. This guy wanted a cheaper raid solution than going w/ a LSI megaraid 1600, some people suggested software raid, but there goes part of why we use scsi :(

And I'd think raid5 would especially put a load on the cpu rather than a raid0 too. Not everyone has a 4Ghz vert ;).


to the original poster: do you really need all that space for your server? If this is for some big company I think they would be using something slightly more manly that serial ata and ide. fibre channel scsi? I don't know much about fibre channel (from what I hear it is not for people running scsi on their linux pcs at home for the most part :p ), but all I know is that it is used for serious stuff (that is what they run here at work anyways I hear, yeah yeah I should know more, but I'm just a coop :p ).

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Originally posted by ua549
Your system would be quite slow. Software RAID is a very big burden on the CPU. Not only that, you must also have a basic volume from which to boot because dynamic volumes are not bootable.

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Yes dynamics are not bootable but it appears he is booting off of another drive anyway since he said this:

"In disk manamgement, I had the option of spanning the two stripe sets together, as well as striping the two stripe sets together. "

If he had the option to stripe them then he must not be booting off them correct? You can't stripe a drive you just booted off of.

I may be wrong, but it still seems to me that you wouldn't lose that much performance (as long you have a halfway decent CPU) by using the Software Raid 5 and it seems a much better option than 4 striped disks. If any one of those disks goes down there is going to be some data loss.:)

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Originally posted by vertices




it seems a much better option than 4 striped disks. If any one of those disks goes down there is going to be some data loss.:)

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yeah I had to deal with that crap a year ago, crew stripping I say (unless you are deallign w/ some very reliable stufff, but 4 striped disks is horrible... I still don't see why you'd use ata for a enterprise level server? Is this like a small company we are talking about here?

Originally posted by vertices

Yes dynamics are not bootable but it appears he is booting off of another drive anyway since he said this:

"In disk manamgement, I had the option of spanning the two stripe sets together, as well as striping the two stripe sets together. "

If he had the option to stripe them then he must not be booting off them correct? You can't stripe a drive you just booted off of.

I may be wrong, but it still seems to me that you wouldn't lose that much performance (as long you have a halfway decent CPU) by using the Software Raid 5 and it seems a much better option than 4 striped disks. If any one of those disks goes down there is going to be some data loss.:)

First, he does not need dynamic disks to use a hardware stripe set.
Hardware stripe sets are bootable. Having options to span or stripe his current volumes presented in disk manager does not mean that the drives are currently dynamic volumes. Had one of those options been selected disk manager would then ask about converting the basic volumes to dynamic volumes. He would see the appropriate warnings and error messages about not being able to convert the system volume.


Originally posted by vertices
Wouldn't another logical "cheap" method here be to just set up all 4 disks as independent disks on the hardware raid controller and then just RAID 5 them through Windows Server?

You under estimate the impact of software RAID on disk performance as well as CPU utilization. It is quite significant even with a 3 GHz proc.

He would need a basic volume (outside of the RAID 5 array) as a system volume.

You are right about the risk of data loss. A 2 drive stripe set doubles the risk of losing all data on all drives and a 4 drive stripe set quadruples the risk. Personally, I'm not that brave! I much prefer RAID 1 (mirror) and RAID 5 (stripe set with parity) combined into a RAID 5+1 arrangement along with tape backup every day.

hey ua549 do you think it would be too much a risk to raid a pair of Cheetah 15K drives in raid0? They are pretty reliable for that I would think, and I'd have plenty of backup on ide drives too (yeah I neither have a second Cheetah nor a raid card, this is just wishful thinking :) ).

I won't do it myself (and I have 7 Cheetahs) so I can't recommend that anyone else do it.

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Originally posted by ua549
First, he does not need dynamic disks to use a hardware stripe set.
Hardware stripe sets are bootable. Having options to span or stripe his current volumes presented in disk manager does not mean that the drives are currently dynamic volumes. Had one of those options been selected disk manager would then ask about converting the basic volumes to dynamic volumes. He would see the appropriate warnings and error messages about not being able to convert the system volume.

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I understand the difference between hardware and software RAID.:) I understand that you can boot off a hardware stripe set. But he was talking about being in Disk Managment in Windows and having the option to create a stripe set from his disks which implied to me that he was not booting off them.

I guess I just forgot that it will allow to do it and then give errors. For some reason I remember it not even giving you the option if you are on the system volume.:)

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Originally posted by ua549
You under estimate the impact of software RAID on disk performance as well as CPU utilization. It is quite significant even with a 3 GHz proc.

He would need a basic volume (outside of the RAID 5 array) as a system volume.

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OK...I guess I underestimated the impact.:) But, if the impact is so HUGE why does anyone use it then?

Yes I understand he would need a separate basic volume, which I thought he already had because I remembered incorrectly how it will allow you to go ahead and then give the error.:)

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Originally posted by ua549
I won't do it myself (and I have 7 Cheetahs) so I can't recommend that anyone else do it.

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just wondering, how many more can you add on? I got into a big debate w/ someone on thsi forum a while back about ultra3 being able to support up to 15 disks. I think older scsi systems were limited to 7 (yours probably is not one of them) but I was just wondering. I read a whole bunch of stuff about it, but there aren't that many people that run that many scsi disks so you are the person to ask :) . Basically from what I got out of various sources was that a good ~ 3 meter SCSI cable should be good for 15 drives...

edit: oh yeah I just remebered, my system manuals and stuff talk about 15 scsi ids on each channel :)

I wish he would answer to me why he want to use any kind of raid0 setup on a server that he'd be relying on, and why not raid 0+1 (hmm I have heard of raid 10, is that the same thing?).

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Originally posted by pudad
I wish he would answer to me why he want to use any kind of raid0 setup on a server that he'd be relying on, and why not raid 0+1 (hmm I have heard of raid 10, is that the same thing?).

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http://www.lsilogic.com/products/sto...grounder7.html

Apparently RAID 0+1 is more like Raid 5. I always thought 0+1 was a combo of 2 mirrored RAID 0 sets.

Check that link out and check the different RAID configs. I guess I was wrong about some of this stuff.

Edit~~~forget it..I can't read diagrams today apparently...thats what I get for posting and talking on the phone at the same time lol!!:):D

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Originally posted by vertices


http://www.lsilogic.com/products/sto...grounder7.html

Apparently RAID 0+1 is more like Raid 5. I always thought 0+1 was a combo of 2 mirrored RAID 0 sets.

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that is what it is isn't it? I swear it is, or at least that is how the highpoint controller on the KD7-RAID says (before smarktards try to bash me for having a KD7-RAID, know that is was a very nice rma from a KR7A-RAID :cool: ).

RAID 0+1 = mirrored stripe sets.

RAID 10 = striped mirror sets.

There is a difference, but IMO it is not too significant because with that many drives different RAID configurations are better.

Yeah it is....lol!! Apparently I'm having troulbe looking at diagrams today! :)

ah now I see, reverse sort of, hehe learn new stuff all the time.

hey ua549, about the # of disks on a ultra3 channel? 15?