Does RAID make a big difference.?

[rudeboymcc]

hi. i have a KT7-RAID abit motherboard. at the moment, i have a cd writer as primary master, the HDD on primary slave, and a dvd player on secondary master. i'm wondering how much difference it would make to my pc if i put the HDD on RAID. this way, everything will be master, and have its own channel.

will this also speed up the signal from the writer to the harddrive, making failed burns leess likely to happen?

[buba king]

if you only have one disc, you wont get any speed increase, unless you have "software raid" (i dont know if your motherbord does) witch will only make your system slower.

[bb]

For RAID you need at least two HDDs, no matter if it's a hardware or software solution. Onboard IDE RAIDs support RAID0 only; this is known as striping without error correction. It increases speed as HDD access is distributed to the connected drives.

For capturing purposes RAID0 is recommended. For encoding, especially "stream copying", two independent discs perform better, if you keep the copy source and target on different drives.

This is not just theory: I own a two-disc PC and a RAID0 PC as well.

bb

[mpucoder]

I have the same MB, and the KT7 RAID supports all three modes (0, 1, and 0-1), but that is not really what rudeboy is asking.
Using a seperate IDE channel for each drive will indeed reduce bottlenecks when copying from device to device.
You already have a very unusual configuration, though - one that would not work with older BIOSes. You should make the HDD the primary master, not just for nostalgia sake, but because you cannot boot from IDE 3 and 4

[Arky]

mmm, but you CAN boot from RAID... (cos I do :cool: )

I run my onboard RAID controller simply as an extension of my available IDE channels, rather than as true RAID. In other words, I use a "JBOD" array, which means there is no true redundancy through mirroring or striping, so there is no absolute performance increase, but bottlenecks are reduced, as mpucoder noted, because if I wish to copy data from one of my CDRWs (on traditional IDE controller) to one of my HDDs on the RAID controller, there is less bus overhead than there would be if the HDD were on IDE1 Master, and the CDRW on IDE1 Slave.

To be honest, I only use the JBOD config because I simply ran out of available standard IDE channels. In the longrun I'll probably buy a 4th HDD and stripe my HDDs in a true RAID config.


Arky ;o)


*******************************************************************
To clarify, ignoring partitions, the following is my physical drive configuration, the point being that RAID offers flexibility even if you don't have more than one HDD with which to create mirrored or striped arrays. Humble JBOD has it's uses :)

IDE1 Master = CDRW
IDE1 Slave = CDRW
IDE2 Master = CDRW
IDE2 Slave = DVD-RW
RAID/JBOD Channel-1 'Master' = HDD boot
RAID/JBOD Channel-1 'Slave' = HDD storage
RAID/JBOD Channel-2 'Master' = HDD storage

[mpucoder]

Looks like I goofed. Yes, the KT7 RAID controller can be set to be the boot device. It was my other add-on raid (in another computer) that would not boot.

[ChristianHJW]

My EPOX DV-A3 mobo has a HPT 370 Raid controller onboard and i love it. I could easily boot from it ( BIOS configurable ) and i swear it brought a performance increase on my ATA 100 drives ( about + 7-8 % ) even if i simply connected them to it instead of using IDE ( no RAID 0 ).

I always had an old 10 GB HDD ( ATA 66, but was now replaced with a 60 GB Maxtor Diamond Max ATA 133 ) connected to IDE primary master, just for 'hosting' the MBR, plus i have a Win2000 installation on there for 'rescue' purposes, although i hardly ever need it.

My main OS always boots from RAID 0 since more than a year now, being 2 cheapo Maxtor 4 H 020 40 GB ATA 100 HDDs, this is reducing boot time by about -35 % compared to booting from IDE single disc.

In short : I love RAID !!

( I even feel it helps to increase HDD life time, but dont know why this could be, its just a feeling )

[Arky]

Originally posted by mpucoder
Looks like I goofed. Yes, the KT7 RAID controller can be set to be the boot device. It was my other add-on raid (in another computer) that would not boot.

Perhaps, but I still agree with the sentiment below :) :

Originally posted by mpucoder

Using a seperate IDE channel for each drive will indeed reduce bottlenecks when copying from device to device.



Arky ;o)

[rudeboymcc]

thanks. that has indeed given me an answer and i will keep my system as it is. i know my setup is unusual, and everyone else thinks so, but my cd writer is very slow, and i found that by putting the HDD on a seperate controller (ie RAID), it reduced the failed burns. i don't know if it's becasue the writer is primary master, and not slave, but it definately stoped me from buying another cd writer.

and one more thing, th eonly setup i had to do for RIAD was in the win xp setup, i had to load some hotpoint drivers that came with the motherboard, and everything's fine after that. ATARAID is available from the boot menu in my BIOS.

[Arky]

Originally posted by rudeboymcc
i found that by putting the HDD on a seperate controller (ie RAID), it reduced the failed burns..

Just out of interest, have you made sure that you are running your CDRW with DMA enabled? If you are not sure, just RIGHT-click on the "My Computer" desktop icon and select "properties". Then go into the hardware devices manager and look in the IDE-ATAPI settings. Find the relevant channel and open up the dialogue. It should say "DMA if Available". If it says "PIO", then change it to DMA.

DMA reduces the CPU load when writing to your drives, and makes buffer underrun much less likely to occur.


Arky ;o)

[masken]

IDE disks of today has so bad general quality, that a RAID card should always be bought with a PC I think... even for your home PC, if you've got data that you don't want to loose. To get a Promise RAID controller on your mobo when you buy a new one only costs a few bucks more and is really worth it.

On top of it all, the disk manufacturers want to lower the warranty from 2 years to 1. That says even more about quality :(

Fortunately, diskprices are also ridiculusly low nowadays :D

An IDE RAID 0+1 solution (Google'd a pic here (http://www.acnc.com/04_01_0p1.html)) with 4 disks will in 3 out of 4 times preserve your data intact, even if 2 disks fails at the same time (note that this also depends on the controller). And it will also deliver GREAT speed and your whole OS will run faster.

The drawback is that it has an efficency level of 50%, meaning that if you put 4 60Gb disks in a 0+1 configuration, you'll get a total of 120Gb of storage.

[rudeboymcc]

Arky, yes both my drives are on DMA if available. the cd wirte is runnning with multi word dma mode 2 and the dvd is ultra dma mode 2.

masken, what do you mean they're only 50% efficient? where's the other 120 GIG gone??

[Arky]

He means that they are mirrored - in other words, the data is not only striped, but also mirrored. When you mirror data, you duplicate data indentically to two disks. This means that if one disk fails/crashes, you don't lose your data because the other disk still has all the data. You can then buy a new HDD and use the RAID software to re-duplicate the data onto the new HDD, so your data is mirrored again. Because mirroring writes the same data to each of 2 disks, you don't see the combined capacity of both disks - all you see is effectively the capacity of one HDD.

Remember that "RAID" quite literally means "Redundant Array of Independent Disks"

Striping, on the other hand, writes (approximately) half the data to one disk, and the other half to another disk. This improves performance because each HDD only has to work half as hard. However, if one disk dies, then you lose all the data from both disks, because the half data that remains on the un-crashed disk is useless without the other half on the crashed disk. Striping DOES let you see (almost) all the combined capacity of the two HDDs in the configuration.

The ideal solution is to use RAID 0+1 which is a combination of striping and mirroring, but this solution is also the most expensive because it requires a minimum of 4 HDDs.


Arky ;o)

[rudeboymcc]

ok. so mirroring is only used to have a backup of ALL your files, ALL the time, and to make changing harddisks easier. is that all it does? so people actually buy two harddisks just in case one crashes??

[destemido]

it may not be that necessary for you...
for a Server.... :D :D :D

[Arky]

Originally posted by rudeboymcc
ok. so mirroring is only used to have a backup of ALL your files, ALL the time, and to make changing harddisks easier. is that all it does? so people actually buy two harddisks just in case one crashes??

In essence, yes, that is what RAID mirroring is all about. As destemido said, mirroring is more of a luxury for single users, but for servers, where there is mission-critical data, mirroring is an absolute necessity unless you are crazy enough to administrate a server without any protection! :eek:

RAID striping, on the other hand, halves your protection, rather than doubling it, but you get a significant performance advantage which may make the tradeoff worthwhile for even a single user (for example if you do a lot of firewire captures, or if you frequently transfer data from one HDD to another (obviously not between each half of a striped array as this is impossible) )

As I said before, RAID 0+1 is a compromise between both options. It is arguably the best option available for a RAID controller, but is costly because you effectively have TWO redundant HDDs (one extra redundant per 'stripe' channel).


Arky ;o)

[masken]

Originally posted by Arky
Remember that "RAID" quite literally means "Redundant Array of Independent Disks"I prefer the inexpensive (http://www.webopedia.com/TERM/R/RAID.html) interpretation :D

Seriously.. the irony hehe.. just two hours after I wrote this, my HDD crashed... would you believe it?! :(

At least it could be the HDD, but I think (hope) it's the mobo or the IDE channels... otherwise it's several days worth of job down the drain :(

'Oh well, finally a chance to connect my Promise controller Iv'e been having lying around for a while, but never connected due to lazyness of emptying my disks... ;)

[rudeboymcc]

masken, how is it possible that you wrote "two hours after i wrote this, my pc crashed"? you can look into the future?? how do you do that? is there a new RAID platinum that has LIF compatibility? (look into future :)) just kiding.

if you're the supersticious type, sorry i opened this thread. if you're not, then bad luck. it's all sorted now?

[theReal]

i have a cd writer as primary master, the HDD on primary slaveJust a comment on the first question: having HD and Burner on the same cable is never a good idea. It can cause problems with setting the right DMA mode for the HD, it can also cause problems with transfers from the HD to the Burner.
Having all devices as single master devices is always desirable - so yes, using additional IDE channels is a good idea.

[masken]

Originally posted by rudeboymcc
masken, how is it possible that you wrote "two hours after i wrote this, my pc crashed"?
Oh my god, it's timetravel :eek:

..or perhaps just two posts? Ot three rather, counting this one :p

and yes, some bad english hehe...