Raid Performace?

[Phatty2x4]

Questions for all of the hardware gurus here

I currently have a Mylex Acceleraid 250 with 8 MB ram onboard.
I have 5 10K 9 gig drives attached to this controller using RAID 0.

I have noticed that once I moved from IDE (be it a single drive or IDE raid) to this set up my encoding time dropped significantly.

I imagine that there a few people that have something similar to this setup in their rigs - what I want to know is for encoding/ripping/ect, will I see any kind of noticeable gain if I upgrade my controller memory from 8 to 32? I want to make sure that the money spent on the upgrade is worth the price.

Along the same lines - is there anyone that uses a SCSI raid controller in a raid 5 setup? Are there any noticeable performance gains or losses using Raid 5(for encoding/ripping/ect)? If the controller has sufficient memory - will there be any noticeable performance gains or losses using Raid 5(for encoding/ripping/ect)?

[Skullworks]

While there has been tremendous advances in EIDE drives, nothing reduces system overhead like offloading disk I/O to a SCSI controller.

Once going to a striped raid you are now able to reach towards the transfer limits of the controller since the data stream is flowing to/from multible drives.

Going from RAID 0/1 to RAID 5 will most likely not show any gains in performance - its for applications where every bit ( as in 0,1 ) is critical - for audio/video this is not a serious issue.

Adding more cache to the controller - the affect from this depends alot on the rest of your system - how much main mem, CPU(s) etc. But don't expect any noticeable gains when ripping. The cache is a great help when there is alot of multi-task I/O inprogress. When doing a divx conversion you have a contigous data streams in and out - so gains in system capability for random I/O won't help much.

( and yes, there is also a 4 drive striped RAID in my system. )

[prom3theus]

Well, since this is a thread about raid performance someone might read when perusing info and considering the outlay of cash to get identical drives (where I was two weeks ago) I can say that my experience has been GREAT with raid, even on slower, cheaper drives. I was using an ata-100 maxtor diamondmax high end 40GB drive for quite a while, using 150mhz performance ram, a 1GHz amd system, and even running my capture at high priority and I still often had shortfalls in my storage ability. I recently purchased two 80GB 5400 ata-100 drives in a highpiont on-board raid controller at raid-0 (of course) and I not only have amazing results (like USB devices causing significant perfomance reduction), I can capture while editing or watching other videos, in raw yuv video at 720x480 (something like 22MB/second or thereabouts).

My system is an abit kt7-raid (drivers upgraded), two maxtor 80GB 5400 rpm ata-100 drives (about $70 each) and a boot drive which is a maxtor 30GB ata-100 drive. My ram is mushkin ram I bought a while back tested to 150mhz, running with an amd 900? t-bird (I overclock always so I'm not even sure what the base is now:).

Considering all my equipment is pretty old now I'd say you could get away with fairly standard ram, an 800mhz or so processor (on-die cache processor), and two fairly cheap 5400 rpm ata-100 drives on a raid controller and have great capture experiences. I wish I had known more about raid back then and I would have scraped together the cash to buy two identical drives at once instead of slowly upgrading one at a time.

Go raid, you won't regret it (unless one of them fails on you:).

[Skullworks]

A striped RAID 0 is great. I prefer SCSI because of the extra flexability it offeres and the reduced CPU overhead.

There are several good EIDE RAID options available, but the worst is the software built-in RAID in W2K or XPpro. If you choose to use EIDE RAID use the Hardware controller, it has a distinct performance advantage over the simple software RAID. These cards can be found very cheap if you look around for a really good deal. Promise Fastrak is a common one.

[prom3theus]

I honestly know nothing about scsi except that until ata-100 and 133 drives that there was no question that scsi was the true prosumer equipment. I actually didn't really believe the RAID hype even when I purchased a kt7-raid a long time ago just to be able to use the highpoint ata-100 controller in an amd chipset (it was one of only a few offering it at the time, and with isa so I could use my true hardware modem for linux). I also didn't have money to buy two identical hardrives at a speed high enough for good video capture. I just recently used the onboard highpoint raid controller and I have no problems with it directly (updating the drivers from the FAQ site first). I DO have serious problems trying to scandisk (or norton etc) the drive to fix errors in the FAT. I'm currently missing about 30GB in my 150GB raid array because I crashed and the drive space is messed up.

Anyone know of a program that can be used well to scandisk a raid array? Even after doing the vcache change in system.ini I still don't have memory to scandisk the drive. Did I screw up by not using a 64K cluster size? No FAQ I saw even mentioned potential problems like this, with programs that really are absolutely essential. I already have gigs of data on the drive, I can't just repartition it. Will something like PQMagic allow me to change the cluster size dynamically with data on it?

[FWMan]

FireWire RAID.

As Unplugged pointed out in this forum, and I would like to quote:
This is true but I remember you that SCSI harddisk mechanics head(s) can read 1 seek point per time, this is in the physics of drives.

So the "multiple concurrent user connections" that SCSI improves is mainly due to interface connection:

- SCSI excellent instant and parallel I/O concept (multi-unit>read/write)
- Advanced controller
- Hardware caching capabilities
- Genuine driver support


And I'm totally agree with Skullworks it's bad combination of IDE drive and IDE bus.

I still use the low cost of IDE but give them a kick with FireWire touch...
pls refer to my set up at
http://forum.doom9.org/showthread.php?s=&threadid=31702&highlight=RAID

I move my box anywhere I want and have instant RAID0 (well only on Win2K and XP).

[prom3theus]

To reply to myself so people might be able to search for this in this forum:

The scandisk out of memory error inside windows is due to a limitation of something like 2million clusters (this info is found elsewhere).

What I didn't find elsewhere is that you can simply exit into dos mode and scan the drive using the DOS scandisk version (at least it worked fine for me for my 150GB raid 'drive' using windows 98 (second ed)).
Not exactly a great solution (post-partition), but it seems to work.

Thanks again Bill for such wonderfully robust software:)