Does raid config. really help performance?

[DARRIN]

What kind of benefits does using a raid configuration have? Would I see improvements in games, like loading up the game and switching levels?

 

[dew042]

well its gives higher sustained tranfer rates for large files at the cost of slower seek rates and access times.

for the most part i have found the differences very minute in real performance.

it would be great from graphic design or something that transfers big files a lot.

dew.

 

[Zach]

Originally the point was redundancy.. something forgotten by too many home users today.

 

[jthsmak]

ouch zach, what about a raid 0+1? A compromise?

 

[DARRIN]

What is the diff. between raid 0 and raid 1?

 

[SCSIRAID]

RAID 0 "Stripes" or distributes the data is small chunks over multiple disk drives so that when a read or write occures you have multiple drives transferring the data in parallel. For large acceses (relative to the stripe unit size) you can get quite good accelerations. For accesses that are near the stripe unit size it is pure overhead and can slow you down.

RAID 1 is "Mirroring" where 2 (or more with 0+1) drives are maintained as exact copies of one another. If one dies.... your data is still available. You can then replace the failed drive and the array will be rebuilt to be redundant again.

As to RAID being only for redundancy... RAID 0 was in the original paper and it didnt include redundancy. In the timeframe it was proposed... disk drives were dog slow (not to mention small) for the affordable ones. You could consider an array of say 8 ESDI drives running spindle sync'd with the stripe unit size of 1 bit. That would fly if you did all the assembly/disassembly and control in hardware. It would provide acceleration for all access sizes with such a small stripe unit. What I am trying to say is that RAID 0 is not useless... we just dont have the kind of disk hardware today to really make it fly (no direct control of the media format.. hard sectoring.. spindle sync etc etc)

 

[zoom8112]

raid 0 is disk striping = better performance
raid 1 is disk mirroring = two identical hds, no perf gain but there is redundancy

for gaming, i would go scsi

here is what i have learned: modern games nowadays rarely hit the hard drive after the initial load up...

but when it does, scsi's faster access times will help the game load faster whatever it needs to, levels, skins, etc...

but, sustain transfer rates of scsi are not as good as a clean ide raid array (ibm 60gxps), so if you plan on doing any video editing or anything to do w/ moving, manipulating large files, gotta go w/ the ide raid array

then there is also the price issue of scsi; you can probably get a 3-4 ide hd raid array w/ ~100gig of space for the same price as a 19160 and x15 cheetah 9 or 18gig

i kinda dont think the price justifies the performance, but thats just my humble opinion..(scsi that is)

 

[zoom8112]

"Originally the point was redundancy.. something forgotten by too many home users today."

thats why we have 16x plextors

 

[zoom8112]

actually in raid 1 there is a perf gain in read speeds

my mistake..

 

[zoom8112]

.

 

[Helznicht]

Is there a performance gain in writing to a Raid 0 array ?

 

[zoom8112]

good question

try reading this link

its a very well written article

 

[MichaelD]

Hi Darrin,

I asked myself that question about 6 weeks ago. I went with a RAID 0 setup (two Maxtor DM+ 40 giggers) on the onboard RAID controller of my mobo (Abit KT7R) After formatting and all that, I have a 76 gigabyte virtual drive.

Here's the scoop.

1. It was very easy to setup. I played w/the stripe size and settled on 64kb, that's the highest the Highpoint controller will let me set. The 64kb stripe scored a bit higher in SANDRA and HDTach, so I went w/that. Also, the excellent AT RAID article from about 6 weeks back showed that w/the Highpoint controller, bigger stripe sizes are better in RAID O. So I went w/the biggest stripe size I could.

2. Benchmarks; ah we all love dem benchies! There is no contest; RAID 0 beats the pants of a single IDE drive. More than twice the burst speed, almost twice the sustained transfer and seek times are about 4 ms faster.

3. Realworld. Honestly, it's faster, but nothing that will make you go "ooh-ahh". Well, I AM used to it...every little bit of speed is noticeable to me.
Big games like Q3A and UT load faster. Prolly about 20% faster...that's just my guesstimate though.

I'm glad that I did it though. Faster is faster, period. There are lots of folks who say "just get a 5 gig SCSI drive and put you OS on that." I don't see the point to that. You want your apps to load faster and you want your data transfer to be faster. Who cares if the OS loads in 8 seconds as opposed to 10? I don't start clicking until the hourglass goes away anyway...wanna make sure Mr. Registry is all comfy B4 I start messing around,you know!

RAID 0+1 is nice, if you can afford 4 HD's, but RAID 0+1 is slower than RAID 0 and from a performance standpoint, speed is what U want, right? Most of us have all the CD's for all our Proggy's and Apps. What we don't have, we can DL off the net and we all have CD burners, right? If my array went south, yeah, I'd be pissed, but I wouldn't lose much, if anything. I have all my photos burned on CDs. All my UT levels I DL'd (I love that game!) are on CD as well.

Go for it, Darrin.

 

[DARRIN]

<< Go for it, Darrin >>



I might just do that when I get my A7N266 in a couple of months.

thanks everyone for the info.

 

[Zach]

<< ouch zach, what about a raid 0+1? A compromise? >>



A freaking waste, the redundancy of RAID 5, but loosing half of your drives! Terrible. And, RAID 5 requires either a processor on the RAID card or sucks CPU cycles, so unless you have money it's not viable. RAID, unless hardware prices can drop more (for hardware RAID) just isn't that viable for home use. And, even if it gets cheap enough, for most people a single 100GB drive would still be better than 3-4 30's.

I also think you people using RAID 0 are playing with fire. Ever have a hard drive die? I so use it, for a program partition to make better use of mismatched 10 and 20GB drives. My OS is on the first 10 of the fasster 20GB dive, a D: partition for programs the latter 10GB and the single 10GB drive. It is much faster, but I only put games on it. Is saving a second or two when you load a couple programs worth all the time it takes to start from scratch? Noooo, unless you like it (I use to, some of you probably like starting fresh). But no need to start fresh with Win2K.

This will all really come into focus if you loose a hard drive too, a Fujitsu just died on my Thursday so I'm a bit sore.

 

[Zach]

<< actually in raid 1 there is a perf gain in read speeds

my mistake.. >>



Only if the controller or software is smart enough, I've heard conflicting stories on this so I gues some of the IDE RAID cards must not take advantage of two drives to read from. It's supposed to be like 50% (ideally).

 

[Helznicht]

So zoom, it looks like the answer is yes, but after some major tweaking.

Do you forsee having this much trouble getting onboard raid writes to perform properly. I am considering a MB upgrade to add raid capability. This is mainly for digital video editing, and I sure dont want to DECREASE my write capability.

Thanks for the link!

 

[zoom8112]

well for digital editing, maybe you could have a large raid 0 array and then back up your important data on a slower 'backup, storage only' large single drive..???

that way, you have the high perf of the raid 0 array, while having security in the single drive

if you do get a motherboard w/ onboard raid, try to get one w/o the hpt370; although its a good performer, people have been reporting that its picky and rather buggy (i've never had problems w/ mine)

so try to look into a board w/ an ami megaraid (found on iwills) or a built on fastrak (found on asus boards)

btw, what config are you planning to get???

 

[zoom8112]

&quot;Only if the controller or software is smart enough, I've heard conflicting stories on this so I gues some of the IDE RAID cards must not take advantage of two drives to read from. It's supposed to be like 50% (ideally). &quot;
-------------------------------------------------------------

theoretically, its suppose to read twice as fast but we all know, 'real world' perf is diff from theoretical

it makes sense in a raid 1 config because the controllers can read the date off both hds thus reducing read times.....

 

[DARRIN]

Is the built in raid capability on the Asus boards as good as having a seperate controller?

 

[zoom8112]

the perf of the two are about the same, reason being is that they are both 'software' raid controllers, analagous to winmodems...

but if you get a true hardware based controller like ones from 3ware or adaptec, perf would be higher because those controllers have onboard processors that handle the 'raiding'

also the true hardware controllers dont tax the cpu the way the software ones do, although they dont tax it that much..

 

[MichaelD]

There are two diff types of controllers; software and hardware. The onboard Raid controller on mobos like the Asus and Abit are considered Software. They are basically IDE controllers dedicated to raid, with NO additional RISC processor to calculate the striping. The software controllers use CPU cycles to do that.

Hardware PCI controllers have a built in processor that does the striping and other Raid-type calculations (my, Mike, how technical! ) and they hardly use any CPU cycles at all.

The main diff is price. Even a &quot;cheapie&quot; hardware Raid controller is at least $250. I considered one briefly. Raid is more of a toy for me than a necessity. If the time comes that I don't like it, well, then I'll have three HDs to play with.

 

[zoom8112]

i just want to iterate that when setting up a raid array, for max perf, each hd should be on its own channel

this will avoid the multiple requests of two devices on one cable, therefore hindering performance..

 

[Helznicht]

definatly looking at hpt370, the one on the BE62 rev2 board.

 

[zoom8112]

excellent board..

long live the bx!!