All this talk about RAID

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March 8th, 2004, 11:47 AM
Gollo

All this talk about RAID

Ok well now I'm curious. I've searched google and haven't found anything that really answers my question so I thought I'd ask here.

I am looking at building a server for a small business. They recently had a hard drive crash and didn't have recent backups so now they are looking for redundancy along with the backups. What I'm looking at is a gigabyte board with SATA RAID 0,1,0+1 built in. I would be running it in RAID 1 with two 120GB seagate drives. Anyways my question is this, os aside, lets say I have both drives up and running and all is well but drive A decides to crap out on me. Does drive B continue to run without any problems or do I have to put in another drive for it to mirror to before it will work normal like. Could I just pull the drive out of raid and put it as a standalone drive and have it work? I just want to know that if I have a hard drive crash the system will continue to work (or work with minimal configuration). Thanks in advance.
March 8th, 2004, 11:59 AM
kato2274

Quote:

Originally Posted by Gollo

Ok well now I'm curious. I've searched google and haven't found anything that really answers my question so I thought I'd ask here.

I am looking at building a server for a small business. They recently had a hard drive crash and didn't have recent backups so now they are looking for redundancy along with the backups. What I'm looking at is a gigabyte board with SATA RAID 0,1,0+1 built in. I would be running it in RAID 1 with two 120GB seagate drives. Anyways my question is this, os aside, lets say I have both drives up and running and all is well but drive A decides to crap out on me. Does drive B continue to run without any problems or do I have to put in another drive for it to mirror to before it will work normal like. Could I just pull the drive out of raid and put it as a standalone drive and have it work? I just want to know that if I have a hard drive crash the system will continue to work (or work with minimal configuration). Thanks in advance.

I believe that in this scenario, you get a warning that a drive has failed but the volume set will continue to run. the writes will just be done the good drive. when you add another drive in, you simply rebuild the array. probably takes 20-30mins or so. I don't believe that you can put the good drive in another system as a stand alone. (I could be wrong about that though.)

if the board will let you do it, RAID 1 with an online spare is the best option. if one drive fails, the spare automatically replaces the failed drive. when you replace the failed drive it becomes the spare.
March 8th, 2004, 12:16 PM
Matridom

Quote:

Originally Posted by kato2274

I believe that in this scenario, you get a warning that a drive has failed but the volume set will continue to run. the writes will just be done the good drive. when you add another drive in, you simply rebuild the array. probably takes 20-30mins or so. I don't believe that you can put the good drive in another system as a stand alone. (I could be wrong about that though.)

if the board will let you do it, RAID 1 with an online spare is the best option. if one drive fails, the spare automatically replaces the failed drive. when you replace the failed drive it becomes the spare.

The drive would be accesible as a standalone drive in another system(raid 1 only) , but if you try to boot from it, it will still have the issues that you would have if you tried to move windows from one computer to another. If this system is for a small business where data is very important, you will still want regular backups done and taken offsite, you may also want to look into raid 3 and 5 options if they are truly serious.

Swapping the hard drive.. Depends on the raid card you have, some of the good scsi stuff let's you hot swap the drive without even rebooting, it will rebuild it on the fly. Most IDE drives will "clone" the drive during boot (talking 15-20 minutes here. Some will let you do it in windows, but your OS will crawl for the next hour while it copies things over and tries to keep up with windows.
March 8th, 2004, 04:17 PM
Gollo

Quote:

Originally Posted by Matridom

The drive would be accesible as a standalone drive in another system(raid 1 only) , but if you try to boot from it, it will still have the issues that you would have if you tried to move windows from one computer to another. If this system is for a small business where data is very important, you will still want regular backups done and taken offsite, you may also want to look into raid 3 and 5 options if they are truly serious.

Swapping the hard drive.. Depends on the raid card you have, some of the good scsi stuff let's you hot swap the drive without even rebooting, it will rebuild it on the fly. Most IDE drives will "clone" the drive during boot (talking 15-20 minutes here. Some will let you do it in windows, but your OS will crawl for the next hour while it copies things over and tries to keep up with windows.

Backups are definetly going to take place. I was just wondering how much down time they would expect if a hard drive in the array went down. If it will keep humming except for a reboot to install a new hard drive then that's not a problem. As for pulling it out and putting it in a standalone system I meant in the same system just remove the raid and have it run as hd1 on the system. I think that I'm convinced that it will continue to work even if one of the drives drops. Now for the big question. How well does SATA and/or SATA RAID play in linux. Thanks guys.
March 8th, 2004, 04:54 PM
Matridom

Quote:

Originally Posted by Gollo

Backups are definetly going to take place. I was just wondering how much down time they would expect if a hard drive in the array went down. If it will keep humming except for a reboot to install a new hard drive then that's not a problem. As for pulling it out and putting it in a standalone system I meant in the same system just remove the raid and have it run as hd1 on the system. I think that I'm convinced that it will continue to work even if one of the drives drops. Now for the big question. How well does SATA and/or SATA RAID play in linux. Thanks guys.

It's hardware based, so the OS does not matter. As for standalone in the same system, it will work *IF* it's on the same controller, i had tried it on my fastrack IDE raid card. The only linux issue I would see is support for the raid controller, if that works, should be fine.
March 8th, 2004, 06:15 PM
Gollo

Quote:

Originally Posted by Matridom

It's hardware based, so the OS does not matter. As for standalone in the same system, it will work *IF* it's on the same controller, i had tried it on my fastrack IDE raid card. The only linux issue I would see is support for the raid controller, if that works, should be fine.

Well now I'm sorta worried. After doing a lottabit of digging I came across this website and it mentions that most controllers need a software driver to make them work and are thus not true raid. Is this true or is the software only for mirroring but as far as fail over the hardware takes care of this? Grrrr.... Just when I thought life would be easy.
March 8th, 2004, 06:35 PM
Matridom

Quote:

Originally Posted by Gollo

Well now I'm sorta worried. After doing a lottabit of digging I came across this website and it mentions that most controllers need a software driver to make them work and are thus not true raid. Is this true or is the software only for mirroring but as far as fail over the hardware takes care of this? Grrrr.... Just when I thought life would be easy.

I've had a fastrack66 card for about 3-4 years now, one of those ultra66 that you could convert with some creative soldering. I KNOW mine does it in hardware, even at the command prompt, i get the proper size for my disks (mirrored) I've also seen it mirror drives when powering up. The "software" that windows uses is to interface to the card to monitor the array and make sure everything is hunky dory and give big fat warnings if S.M.A.R.T. picks anything up.

SATA, not sure about how the new controllers work.
March 8th, 2004, 07:14 PM
kato2274

Quote:

Originally Posted by Gollo

Backups are definetly going to take place. I was just wondering how much down time they would expect if a hard drive in the array went down. If it will keep humming except for a reboot to install a new hard drive then that's not a problem. As for pulling it out and putting it in a standalone system I meant in the same system just remove the raid and have it run as hd1 on the system. I think that I'm convinced that it will continue to work even if one of the drives drops. Now for the big question. How well does SATA and/or SATA RAID play in linux. Thanks guys.

I just installed sme on a raid 1 system with a Iwill IDE RAID controller. no problems that I can notice.
March 8th, 2004, 10:14 PM
avi8tor

I am currently using SATA Raid 0. I am using 2 hd in an array for speed. I don't and any corruption problems and is fairly fast. If you want redundancy and a reliable backup use Raid for mirroring the main drive. If the primary drive fails then the mirrored drive will boot and take over. The ideal setup - in my opinion - is to have 4 drives of equal size and type, 2 setup in a raid 0 and 2 setup in raid 1.This way you get the speed of raid and the mirrored backup for safety of data. If a drive in a Raid 0 fails then the entire raid 0 array is gone and the data cannot be retrieved thus the need for raid 1 for mirroring. Hope this helps. Good Luck !
March 8th, 2004, 10:48 PM
Gollo

Quote:

Originally Posted by kato2274

I just installed sme on a raid 1 system with a Iwill IDE RAID controller. no problems that I can notice.

I might have to look into ide then. I would really like sata but if it's to new then I'll have to go with what works. Thanks for the info.

One other thing thought that I've come across is "inteliigent" controller and "non-intelligent" controller. What's the difference?
March 9th, 2004, 08:39 AM
Linthade

For a hardware controller to do proper raid it needs to have an on-board BIOS that can setup the logical drive on its own. If it can accomplish that, then the OS truly does not matter.

My personal raid choice of implementation is raid 5, running three drives for zero downtime. One drive fails, swap it out and move along. Zero downtime.

*lin*
March 9th, 2004, 10:05 AM
kato2274

Quote:

Originally Posted by me

I just installed sme on a raid 1 system with a Iwill IDE RAID controller. no problems that I can notice.

Quote:

Originally Posted by Gollo

I might have to look into ide then. I would really like sata but if it's to new then I'll have to go with what works. Thanks for the info.

One other thing thought that I've come across is "inteliigent" controller and "non-intelligent" controller. What's the difference?

well I guess I spoke to soon. it appears that although I installed SME server with my drives hooked up to the raid controller and an array built, sme since it doesn't support the raid controller as a scsi device is seeing both drives seperate and really only working as it would in a single disk system. so I'm probably pop the card out and just hook them up to the mainboard IDE and use software RAID mirroring.

it seems that redhat 7.3 which SME 6 is built on only really supports 3ware raid cards which are expensive.

to try to answer the other question. I believe (and I could be completely wrong) that an intelligent controller is one that as Linthade said has it's own bios and can create the logical drive.
March 9th, 2004, 01:10 PM
tommo666

Have a look at this, it supports most of common Linux distros

http://www.highpoint-tech.com/USA/rr1640.htm

plus it will do raid 5
March 9th, 2004, 06:29 PM
silencio

Quote:

Originally Posted by kato2274

is seeing both drives seperate and really only working as it would in a single disk system.

That is the weirdest thing I've heard in awhile...
March 9th, 2004, 07:36 PM
kato2274

Quote:

Originally Posted by silencio

That is the weirdest thing I've heard in awhile...

well I think it's using the raid contoller as if it were a simple plug and play IDE controller without raid. . . I don't know it seems weird to me too. I'm either just going to do software raid in linux or install 2k server and run it off the hardware mirror. haven't decided which yet. I imagine it'll end up being linux since . . . well . . . it's free and 2k server isn't . . . . oh well
March 10th, 2004, 01:38 PM
Gollo

Quote:

Originally Posted by kato2274

well I think it's using the raid contoller as if it were a simple plug and play IDE controller without raid. . . I don't know it seems weird to me too. I'm either just going to do software raid in linux or install 2k server and run it off the hardware mirror. haven't decided which yet. I imagine it'll end up being linux since . . . well . . . it's free and 2k server isn't . . . . oh well

Yeah that's what I read (I think it's in the link I posted). Since they are not true hardware raid (ie with it's own bios and all that stuff) then it just turns it into a controller.

About software raid. How well does that work? I'm not worried about overhead I just want to know that they system will still run after a drive fails an all's I or anybody else will have to do is pop in a new drive and have the raid restored.
March 10th, 2004, 01:41 PM
Gollo

Quote:

Originally Posted by tommo666

Have a look at this, it supports most of common Linux distros

http://www.highpoint-tech.com/USA/rr1640.htm

plus it will do raid 5

Hmmm that looks good. Price isn't to bad neither (90 bucks at newegg).

/me goes off to research
March 10th, 2004, 01:57 PM
kato2274

Quote:

Originally Posted by Gollo

Yeah that's what I read (I think it's in the link I posted). Since they are not true hardware raid (ie with it's own bios and all that stuff) then it just turns it into a controller.

About software raid. How well does that work? I'm not worried about overhead I just want to know that they system will still run after a drive fails an all's I or anybody else will have to do is pop in a new drive and have the raid restored.

I was just reading up on it yesterday for SME linux and it looks like it works fine. the system continues to run. there is a little more involved then just tossing a drive in, but it's really not that complicated either. here's the HOWTO I found.
http://www.e-smith.org/docs/howto/RA...ery-howto.html
March 10th, 2004, 02:04 PM
Gollo

Quote:

Originally Posted by kato2274

I was just reading up on it yesterday for SME linux and it looks like it works fine. the system continues to run. there is a little more involved then just tossing a drive in, but it's really not that complicated either. here's the HOWTO I found.
http://www.e-smith.org/docs/howto/RA...ery-howto.html

Hmm good info. I'll have to look into that. right now I'm looking at another all in one distro like sme that offers a few more features (www.clarkconnect.com). SME just ran really slow on my system for some reason (not the actuall os just like loading the manager and all that stuff. plus the templates where an extra added step that I don't like very much)
March 10th, 2004, 02:12 PM
kato2274

Quote:

Originally Posted by Gollo

Hmm good info. I'll have to look into that. right now I'm looking at another all in one distro like sme that offers a few more features (www.clarkconnect.com). SME just ran really slow on my system for some reason (not the actuall os just like loading the manager and all that stuff. plus the templates where an extra added step that I don't like very much)

yeah I ran into that template issue the last time I used it and wanted to modify squid to authenticate users to the proxy and not just grant everyone access. this time it's just a simple DHCP/mail/file server, so I don't need any add ons or anything other than a base install. I still may go 2k server, but the geek in me feels compelled to use linux for the cool/geek factor (very strange, I can't quite explain it)

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