Software RAID

[Joeman]

If Tom ever reads this thing I think he should do a comparison between a motherboard with RAID running w2k and a motherboard without RAID running Mirroring or Striping with the Software RAID controller in W2k. I believe the performance diff. will not be that great.

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[Guest]

dude,
Hardware raid is much superior to software raid at any level! That's not saying that software raid is no good, but it's just better than none at all. Compare anything hardware to software and see what you come up with, hardware prevails. An example is software rendering a 3d image or hardware rendering. Which is better? Route network traffic with a software proxy or a hardware router, which is faster and more dependable? Although software and hardware can do the same job, the hardware level is always accessed before the software level (i.e. BIOS/Firmware controlled or OS controlled), increasing speed and reliability.

 

[Lucol]

Hardware RAID is definitely superior. For one, you can add drives on the fly and expand the drive array without taking the server down. Software RAID uses CPU time, while Hardware RAID doesn't. Take it like the difference between running your hard drive in PIO mode and in DMA/UDMA mode...trust me, there's a difference. Software RAID is good, because it's "free", that is it comes with WinNT/Win2K, but it's never superior to Hardware RAID, especially the flexibility and reliability that hardware RAID gives in comparison. I can't be certain about Win2K, but in WinNT, if you lost your OS, whatever you had in your Software RAID was lost, unless of course you made a drive configuration disk under Disk Manager. With hardware RAID, you don't have this problem.

 

[AMD_Man]

But aren't today's mainstream IDE RAID controllers operated by software? What I'm saying is, mainstream RAIDs are always software so I don't think there's a difference.

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[Guest]

Speaking of RAID, I have ordered MSI 815EP Pro-R mobo, which includes a RAID controler. I have heard that I can connect there some IDE devices , such as Hard disks or CD Roms... But I don't have a clue on how I can do this! Is there anyone who could clear the things up for me? thanx in advance
stark

Blue Skies Bring Tears

 

[Guest]

hardware raid cards are identified to the OS via software, the actual RAID is done with hardware. Drivers do nothing more than tell the OS how to address the hardware. I have a 3ware 8 port IDE RAID card with 4 30s and 4 40s on it and it works beautifully. Low cpu utilization and excellent software monitoring... the only thing is I can access this raid array in dos because there is hardware doing the actual RAID, not a software driver...

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[cavemann]

That is certainly correct for the 3Ware cards.
However, most low-cost IDE raid controllers like the Promise FastTraq and similar don't have an on-board processor and perform the RAID functions within software (onboard Firmware).

 

[flamethrower205]

I'm looking for a 2 channel Raid controller, and is there a low cost quality one that does the necessary operations by its own processor rather than software? From what I just read, would teh fastrak be like a software RAID controller?

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[Guest]

The promise cards do the raid on the card. Period. If they were software based they would not be accessible in dos. The promise controllers do use slower and cheaper chips that sacrafice performance and cpu load, but they are NOT software based. You do not need a driver to access the array. A software RAID would NOT be bootable. Promise cards are.

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[flamethrower205]

Sacrifice performance in what sense? Will my transfer rates be slower or something?

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[Guest]

The transfer rates on a promise card in a RAID 0 array will be much higher than a single drive... the RAID 0 transfer rates will be close for a promise raid card and a high end raid card... the cpu usage will be lower on a high end card... the difference comes in raid 1 or raid 5 (which the promise fasttrack cannot do)... Raid 5 (one of the most redundant forms of raid) requires more advanced hardware, but is more reliable... If you are running RAID 0 with 2, 3 or 4 drives and any drive fails, all of the data on all of the drives is gone... no recovery, no options... its gone... RAID 1 is great for backups, but you lose an entire harddrive to backup... for example... raid 0/1 with 4 40gig harddrives makes 1 80gig striped array, redundant, for a total of 80 gigs... raid 5 with the same 4 40gig drives makes one 120gig array of redundant space.... but does not give you the speed boost that raid 0 does... its all trade-offs... raid 0 = fast, unreliable, no space lost (2x80gig = 160gig)... raid 1 = need 1 extra, identical drive for every drive used (2 60gigs = 60gig)... raid 5 = lose 1 drive of up to 8 drives to parity per array (8 40gig drives gives you 280gig of space, 7 20s gives you 120gig of space, 4 40s gives you 120gig)...

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[Guest]

ok that was confusing...
raid 0 = temporary FAST storage
raid 1 = very secure storage
raid 5 = mass storage

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[Guest]

The difference is similar to a hardware based modem and a winmodem. the winmodem is obviously hardware as its a chip you instal into a pci slot but it uses the cpu to do the actual work of processing the data. a hardware modem is faster in the sence that it has a small processor built into it that does most of the data crunching, thereby sparing the cpu from an additional load. both are hardware solutions with slight differences. and both are not dependant upon a particular operating system or file system like NTFS.

the same is true for RAID controllers. some use the cpu to crunch the numbers, other dont. a software RAID solution involves no extra hardware such as a controller. in windows 2000, you can implament RAID with three or more hardrives (for RAID 5 in Server). this requires no special hardware, therefore it is software raid and con only bu used and recognized by windows 2000 pcs. no dos, no linux, etc.

ignore everything i say

 

[Guest]

yah, what he said

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[cavemann]

Yes, The promise cards do perform the RAID functions on-board. However, the promise card is just an ATA100 IDE controller which has RAID functionality built into the onboard firmware.
The drivers do not perform the RAID functionality which is why you can boot from the array and see it in DOS without loading drivers. However it is still a software based solution. The processing is handled by the main CPU and not a dedicated processor like the 3ware cards.