RAID setup information

[Zogthetroll]

ok, i'm getting a little tired of backing up my info on cd's, and i'm starting to look at the possibility of a RAID setup. I'm not sure whether i'd build a seperate server, or incorporate it into my current rig. i'm kinda leaning toward the former though. So I would appreciate if you guys could direct me to some good info on raid setups, the pros and cons of different types, etc. also, what are the advantages of a motherboard w/built in raid, vs. a pci raid card? any help would be great. thanks.

[guandi]

Raid is quite complex for the beginner, and can be very costly.

just be carefull what you do, and read up alot about it. dont go buying stuff that will just sit there for years on end without use, only for it to blow up when you really need it.

[Arcturius]

I wouldn't say it's overy complex...but it _can_ be costly, in certain cases.
This appears to be a fairly decent primer...

It appears that you're simply tired of making backups, and want to be able to recover from a disk failure, without too much effort.

To really give good advice, we'll need to know how much data you have, and how much storage space you plan to require in the next few years. Also, what are your performance requirements, and most importantly: your budget.

If you want to maximize capacity while keeping decent performance, I would recommend a RAID5 array, but it requires a minimum of three disks. In the IDE world, the controllers tend to be overly expensive. For SCSI, the controllers are cheaper, but disks are more spendy.

I am a fan of RAID1, because it doubles the effective reliability of a standalone disk, requires a minimum of only two disks, and boosts read performance.

[Arcturius]

Oh, and I almost forgot: the only advantages to builtin IDE RAID is that it's cheap, and it leaves a PCI slot open.
However, it's still tied to an IRQ line shared by one or more of the PCI slots anyway, and it is a software solution, so will use processor resources (to varying degrees...).

[iroc409]

Originally Posted by Arcturius

I wouldn't say it's overy complex...but it _can_ be costly, in certain cases.
This appears to be a fairly decent primer...

It appears that you're simply tired of making backups, and want to be able to recover from a disk failure, without too much effort.

To really give good advice, we'll need to know how much data you have, and how much storage space you plan to require in the next few years. Also, what are your performance requirements, and most importantly: your budget.

If you want to maximize capacity while keeping decent performance, I would recommend a RAID5 array, but it requires a minimum of three disks. In the IDE world, the controllers tend to be overly expensive. For SCSI, the controllers are cheaper, but disks are more spendy.

I am a fan of RAID1, because it doubles the effective reliability of a standalone disk, requires a minimum of only two disks, and boosts read performance.

actually, i wouldn't really say it's that expensive anymore for the controllers. from what i hear, both highpoint and promise have good ide-raid solutions.

highpoint's entries include the rocket raid 454, which will do raid 5 for up to 8 drives, and runs about $95.

promise is a little more expensive, like the sx4000 at around $150 (4 drive) and the sx6000 (6 drive) at about $250. both units however have onboard memory (pc133), and seem to be a little bit better with raid 5 due to better onboard hardware.

apparently highpoint has fixed their raid 5 woes on their devices, and the hpt374 chip is natively supported by freebsd.

just my $.02

edit: i probably wouldn't be using a highpoint raid 5 setup in the same machine, i would use it in a dedicated fileserver - highpoint cards use more cpu power to do its duties, whereas i _believe_ the promise units are basically all on-board.

[Arcturius]

Originally Posted by iroc409

actually, i wouldn't really say it's that expensive anymore for the controllers. from what i hear, both highpoint and promise have good ide-raid solutions.

highpoint's entries include the rocket raid 454, which will do raid 5 for up to 8 drives, and runs about $95.

promise is a little more expensive, like the sx4000 at around $150 (4 drive) and the sx6000 (6 drive) at about $250. both units however have onboard memory (pc133), and seem to be a little bit better with raid 5 due to better onboard hardware.

apparently highpoint has fixed their raid 5 woes on their devices, and the hpt374 chip is natively supported by freebsd.

just my $.02

edit: i probably wouldn't be using a highpoint raid 5 setup in the same machine, i would use it in a dedicated fileserver - highpoint cards use more cpu power to do its duties, whereas i _believe_ the promise units are basically all on-board.

The hpt 454 uses a hpt374 controller, which is commonly found on motherboards, and is a software solution.
The sx4000 is a much nicer card--but only if you intend to create a RAID5 array--it has an onboard XOR processor, but all other calculations for striping and mirroring are still done by the host CPU.
The sx6000 however, is a _real_ RAID card, as far as I'm concerned. It hosts an i960rm processor, which you should recognize if you've looked at other SCSI RAID cards in the past (the Adaptec 2110Ss I worked with a year ago used that controller). More common now is the Intel 80303--the pin-compatible successor to the i960, which is nearly identical...

Don't count out LSI Logic, either. They make some very nice chips/cards, and their prices are a bit lower than equivalent cards from other manufacturers. They also acquired Mylex a few years back, and some of those cards are still in circulation at VERY low prices (found under 'Lecacy RAID' on www.lsilogic.com).

One other thing to be concerned with, though: many RAID cards are 64b PCI cards, or PCI-X. If you're not planning to run a workstation-level board, you're probably stuck with the lower-end IDE RAID stuff, or SCSI soft-ish RAID (like the adaptec HostRAID, which only does hardware mirroring, but supports host based striping...).

[MadHacker]

cause nobody mentioned it.
there is also software raid.
controlled by the OS.
Windows has it. and if that is the only OS u use that may be the cheepest alternative. but proboly has the most demands on CPU.
my $0.02 worth

[prb123]

I have had good success with 3ware IDE RAID controllers, which can go up to 12 devices and come with single PATA or SATA for all drives that the card supports.

If you want to go SCSI you can get some great deals on older Mylex RAID Controllers which have some of the coolest software (once you can find it...some of the part numbers are kind of cracked out, but they have simplifed the driver sets some what) but do not forget to count the cost for terminated SCSI Cables, and the fact that you will need more drives. Check the hot deals forum at 2cpu.com for good SCSI sources.

[Zogthetroll]

Cool, thanks a lot for the link to that RAID article. that was definately the sort of thing i was trying to find. I was previously confused about the different RAID types. So if i've got this right, raid 1, aka disk striping, doesn't really protect the data from errors(not a huge deal really), more for massive hd failure? or does it have ecc or similar and I just missed that? At any rate, that would be faster, RAID 5 is more concerned with integrity of data on the drive, and actually compares the data coming from the different drives, hence the performance hit. does that sound right? and raid 5 also does rebuilds if a hd crashes?
as for the general performance, space, etc that i'm thinking of, I probably won't use this on my main rig. Mainly what this would be for would be my music collection (i've got my entire cd collection on mp3's on my hd), my web page, which I might try to host once I get rid of this pesky dial-up thing, and a lot of other programs, etc that i've collected. i think 120Gb overall would probably be plenty, and those are seriously coming down in price. I saw a deal recently on them for $60! and i'm not going to be seriously concerned about lag since I would be using this as a fileserver and would be accessing over the network.
on another note, what versions of windows support software RAID, and how buggy is it?
*edit* hehehe, meant to say raid 1=mirroring, but thanks for catching that.

[prb123]

RAID 0 = Striping = Fast but data is gone if any drive fails
RAID 1= Mirroring = Data is good so long at only 1 drive fails.

If you only need 120GB of storage and are not worried about speed Mirroring is the proper setup, infact if you are not worried too much about write times...which you probably are not since it's for your music collection it is probably the best solution (RAID 0+1 or RAID5 is probably overkill).

Windows NT, 2000, XP, 2003/.NET all support software mirroring, I have not seen any real problems with it...I have seen broken mirrors from time to time and have had to re-establish them. However I have never not been able to recover all data after a disk failure.

I still suggest a hardware/semi-hardware based solution.

[iroc409]

haven't heard much about lsi, but i imagine they make decent stuff. i hear the 3ware escalade is a very good card, unfortunately i'm not sure what kind of support there is in freebsd (but, linux and win).

for a dedicated raid 5 setup, i would think the highpoint would be fine. the amount of processor power used would be acceptable if it's the box's only job, and the controller is available on the cheap. from what i hear recent bios updates for the card have fixed raid 5 issues, and have considerably reduced the cpu requirements of the card.

you could go with software raid for win, and i know freebsd has modules built in for raid support as well (read the docs). but i wouldn't suggest that much, ESPECIALLY if you're using it in your exisiting setup, and not a dedicated.

[Boli]

If you can afford it I'm a big fan of RAID 1+0 this may use 4 hard drives but is quite good against hard drive crashes but offers a good performance as well which you might want.

Basically it is a Raid 0 array (striped and a GREAT performer... something I can atest to as I tried it out once) but the Raid0 array is in fact mirrored by the two other hard drives. A RAID1 array of a RAID0 array (thus RAID1+0)... I think that is right way of putting it.

... (either RAID 1+0 or RAID 0+1 I can't remeber which is denotes the better setup... but it is a good system that balanced speed and reliablity. shame it uses 4 physical hard drives though) ....

~ Boli

[prb123]

RAID 0+1 is cool but if he is simply storing MP3 files on it a simple mirror, with two large drives would do fine. Plus the money he saves can be used to purchase a hardware RAID controller.

Ps. I forgot to mention linux, and Novell when stating which operating systems support software mirroring.

[Arcturius]

Originally Posted by prb123

RAID 0+1 is cool but if he is simply storing MP3 files on it a simple mirror, with two large drives would do fine. Plus the money he saves can be used to purchase a hardware RAID controller.

Ps. I forgot to mention linux, and Novell when stating which operating systems support software mirroring.

I agree: Zog's requirements are actually pretty low, and RAID1 fits perfectly, so I would recommend a software based solution like the HPT37x or a Promise unit--whatever happens to be onboard the mobo you like.

I don't think I would recommend a 3Ware card unless somebody intends to build an array on the cheap with tremendous capacity--their 4 and 8 drive models don't compare to competitor's offerings like the LSI MegaRAIDi4, and can't think of a reasonable application for IDE RAID0 or RAID1 in a machine sporting 64bit 66MHz PCI slots...
OTOH, the Escalade x50x-12 cards are a nice way to make a 2TB RAID5 with a hot-spare.

Also, AFAIK, no OS allows bootable OS-software-RAID.

[Grayson]

Hi guys.

AFIK the RAID chips on the motherboard are hardware RAID and thus bootable. You use a special utility to set them up and configure them as the boot device in the BIOS. The only thing lacking is RAID levels above 0, 1, and 0+1 and any RAM cache that the interface cards provide

Grayson

[Arcturius]

Originally Posted by Grayson

Hi guys.

AFIK the RAID chips on the motherboard are hardware RAID and thus bootable. You use a special utility to set them up and configure them as the boot device in the BIOS. The only thing lacking is RAID levels above 0, 1, and 0+1 and any RAM cache that the interface cards provide

Grayson

They are bootable, but still offload all processing to the host CPU, and are thusly categorized as a software solution.

Read up on the way PIO works; it's very similar.

[Zogthetroll]

ok, time to resurrect this thread. getting a little more OS specific here, I was under the impression that windows NT4.0 Server supported RAID 0, 1, 5, and 0+1 software-wise, or will it only manage that with a controller card? I'm in the process (on paper anyway) of designing a server. once i get into a place that I can get broadband instead of dial-up, i'd be using it for a number of functions. it would act as a firewall, fileserver, printserver, and possibly host web pages. I say windows NT4.0 server because i have an old CD of that, i'm willing to live with the lack of USB support, so unless there are any compelling reasons why I should go with a different OS that will do what I want (please let me know if there is, i'm just trying to learn here) i'll use NT. also, when you referred to software solution being non-bootable, you mean off of other than the master drive? my other OS option would be LINUX redhat 7 set up as a server. but i'm not really familiar with that so it'd be a pretty steep learning curve there. anyway, for the server i'm designing, i'm including space for 4 drives so i'll have the option of raid 5 or 0+1 should the need arise. i'm also thinking of going flexATX so if I can use software raid instead of a controller card i'd have room for a tv-tuner card. that's not a big deal one way or the other though. i'll start up a new thread on the server once i get renderings done and specs a little more figured out.

[iggiebee]

Originally Posted by Zogthetroll

ok, time to resurrect this thread. getting a little more OS specific here, I was under the impression that windows NT4.0 Server supported RAID 0, 1, 5, and 0+1 software-wise, or will it only manage that with a controller card?.

Software RAID in Microsoft's jargon, is called "Dynamic Disks", you will find settings under "Administrative Tools" for NT and XP.

[MadHacker]

NT4 has a lot of limitations..
IDE support over 8 gig is one issue if i remeber correctly...
you should try Win2k server... much better and more robust..
terminal services is also a nice option built in

[colintheys]

hey everyone,

I'm an animator and DV editor and I just had my drive die on my, losing far too much data. So, I want to set up a raid now to protect what's left and any future data. However, I'm also a student, so i'm short on the $$$. I have two Maxtor 120gb ata drives (or will once I get the dead one replaced under warranty.) However, 120 is not enough. I need at least 170 (what I have now between three drives.) So I figured that I should get a third drive and go the raid 5 route, giving myself 240gb and a perormance advantage. However, I don't know anything about raid and my research turns up conflicting results. Basically, I need lots of safe, fast storage, I was going to get the highpoint rocketraid 454, but now I'm worried that it will hit my processor performance, which would not be cool, since I animate and edit on this machine. And suggestions would be greatly appreciated.

Thanks,
-Colin Theys

[Arcturius]

Zog: another limitation of NT4 is security (and the lack of updates/support from MS, so the existing security holes will be there forever). Plus IIS is a royal pain, IMO. I think the Fedora setup will let you setup RAID5 during the install if you want, and Apache is fairly easy to use, especially for a single hosted site.
edit: the RAID5 I'm speaking of is the software sort.
also, samba works very well, considering it emulates a very messy, fussy, vaguely-specified protocol

colintheys: RAID5 is very CPU intensive; if you go that route I would strongly suggest a controller with a built in XOR engine, like those listed above.
Then again, you could buy one more 120GB disk (I'm assuming your first three are similar/same in model/performance) and setup a RAID0+1, probably cheaper than buying the fancy controller. You would see a small CPU hit, but nothing too major. OTOH, you would be locked in to that 240GB capacity, unless you later replaced all 4 drives, or got the updated controller.
If you get a different controller, you may be able add a drive on the fly later (depending on SW support, I think the 3Ware cards allow that), and merge it into your existing RAID5 to boost capacity.

hope that helps