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16MB cache on hdd...better than 8 even under RAID 0 ?

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November 13, 2006 12:33:34 AM

Hello...Thanks to read.

I'm building a new computer and wish to use raid 0. i'm not the kind who download a lot of stuff so don't need huge amounts of storage. Two 120GB or even two 80GB may serve me well for years to come. But i've noticed that drives < 250GB have only 8MB cache. Will i see a noticeable performance decrease using those ? The pc will be maily used for occasional photo/video editing, other more common tasks, and more often as an htpc to view/record tv shows and movies via an AIW X1900 card. I'm pretty shure that i'll get anyway more performance with two 0-raided 8MB cache drives than one 16MB cache drive, but need your opinions/thoughts. TIA for your reply.

More about : 16mb cache hdd raid

November 13, 2006 1:33:34 AM

Good question. I hope to hear people's opinion on this too. I'd just like to add one other level. Let's take these two for example:

2 drives in RAID 0 at 10,000 RPM (16 MB cache)
2 drives in RAID 0 at 15,000 RPM (8 MB cache) - SCSI

I assumed the SCSI would be better, but what has been your experience?
November 13, 2006 3:09:58 PM

Quote:
Let's take these two for example:

2 drives in RAID 0 at 10,000 RPM (16 MB cache)
2 drives in RAID 0 at 15,000 RPM (8 MB cache) - SCSI

I assumed the SCSI would be better, but what has been your experience?

Well of course SCSI will be more faster. Its RPM are more faster and SCSI are designed to work more faster. So, even its cache memory are more smaller, the fact is memory speed are more faster than HDD speed. so SCSI memory has refresh rate more higher.

Manufacturer puts lots of cache on big HDD is to help the access to files more faster and reducing head movement. So example :

HDD1 7200 RPM 100GB 16MB
HDD2 7200 RPM 100GB 8MB

You have one file with 16MB size.

You ask HDD1 to execute this file, HDD will search and put it in cache. 16MB cache is full file is executed, emptying cache. Head movements only two times (read, write).
You ask HDD2 to execute this file, HDD will search, put in cache, 8 MB is executed, emptying the cache, read the rest 8MB, put in cache, execute the file. Head movements 4 time (read, write, read, write).

That's just an abstract explanation/opinion. How real is HDD works is really more complicated than that. And i hope i didn't make you more complicated.
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November 13, 2006 3:33:43 PM

Thanks much for the info. :) 
November 13, 2006 7:18:30 PM

In the real world, cache sizes don't make a big difference, but rpm does, because the longest wait is for the physical disk to spin around to where your data is. SCSI, just like E-IDE and SATA, is just an interface; almost always, the throughput is limited by the physical drive, not the speed of the interface. If you have a more complicated setup with multiple drives on a single SCSI string, the SCSI bus speed can become limiting, but that's not the case for almost anything you'll see discussed here.
November 13, 2006 7:28:28 PM

Cool. The fact that the SCSI option is the best choice (faster) is what I was after. Thanks much for the further information.
!