2MB vs. 8MB Buffers

[Xponential]

I've been looking at Western Digital's new special edition HDs that come with 8MB buffers instead of the standard 2MB. I need a new HD for some DV editing I'm doing.

My question is, what's the advantage of buying a HD with a 8MB buffer vs. one with a 2MB buffer?? Looking at the specs, the seek times are the same on both. Shouldn't they be less for the 8MB version?? Or would it be less seek time only when you're transferring huge files??

Any help would be appreciated.

 

[CocaCola5]

Seek time remains the same if the drives plater/rpm remains the same. The buffer helps transfer and probably lowers the load on the cpu also as it doesn't get tasked as much.

 

[Rand]

Seek times, are very similar, and sustained transfer rates are only boosted very slightly.
It does help significantly to reduce overall disk utilization, and disk I/O levels, as well as considerably improving speed when repeatedly accessing and modifying small files such as one would see with some forms of 2D graphics rendering.

As can be seen by Storage Reviews testing of the drives, low level performance characteristics are not significantly impacted... but the overall drive performance is vastly superior then it's 2MB cache brethren.

Their expensive, but if you have the money then they are vastly superior to any other IDE HDD available.

 

[HendrixFan]

If you look at MWave, the difference in price between the 120GB regular and special edition is $20, and the difference in price between teh 100GB models is only $10. Personally, the performance boost you get, as seen at StorageReview is worth the small price increase, regardless of the task you will be doing. Of course, if you are looking at transferring files faster, running two of the 8MB drives in RAID-0 would be pretty impressive. I do alot of video and audio editting myself, and someday Ill run that exact setup.

 

[FishTankX]

My question is this. What keeps somebody from slapping on a 32MB DRAM onto it (Like the Ipod) since RAM is so cheap. The chips are only like, 10$ or so. Andy Hui, you have any input on this?

 

[Dundain]

The RAM chips they actually use on the HDs would make that cost prohibitive and what would be the point? Only a server would require that much RAM on a HD, and even that'd be doubtful. You'd get more benefit from moving towards a RAID array than you would with a cache size that large. There was a really good thread going on on the StorageReview forums about something like this...one of the major things that was also commented on was how it'd require a really rewrite of the caching schemes they use

 

[FishTankX]

But it is my understanding that a generic PC133 32MB DRAM costs along the lines of 5$. Why would that be cost prohibitive?

 

[sharkeeper]

A buffer that large could cause catastrophic data loss if the power fails!

I can see it now...

This hard disk requires an uninterruptable power supply. Failure to heed this warning may lead to an unusable computer if the power fails! :Q

Cheers!

 

[FishTankX]

Eh.. you could make it so that the buffer would only cache 4 megs of data to be written, and use the rest for recently read information. But I see the point. Caching schemes would need overhauls.

 

[FishTankX]

I think you could use Flash as a buffer.. but that would get sorta costly. What about MRAM?

 

[sharkeeper]

Standard DRAM is plenty fast. Anything faster will rarely benefit due to the long signal paths between the HBA and the disk buffer!

Cheers!

 

[FishTankX]

SharkKeeper:I was refering to Flash and MRAM being nonvolatile memory technologies.

 

[sharkeeper]

<< SharkKeeper:I was refering to Flash and MRAM being nonvolatile memory technologies. >>



Well we could keep a 5V 5F cap on the PCB to keep the buffer refreshed!

Cheers!

 

[RaynorWolfcastle]

5Farads?!?!? that must be huge. The largest cap I've ever used was .47 mF and that was the size of a paper back book....

-Ice

 

[sharkeeper]

Huge capacity? Yes! Size is rather small though. 15x10x10 mm square package. Unlike low impedance electrolytic capacitors, these "wet" caps are used in things like VCR's and Phones to retain memory for prolonged periods. Unlike a battery, they can withstand many cycles and have a very long lifespan.

Cheers!

 

[RaynorWolfcastle]

<< Huge capacity? Yes! Size is rather small though. 15x10x10 mm square package. Unlike low impedance electrolytic capacitors, these "wet" caps are used in things like VCR's and Phones to retain memory for prolonged periods. Unlike a battery, they can withstand many cycles and have a very long lifespan.

Cheers! >>



The electrolytic ones are the only ones I've ever used (physics labs in College). What's the difference between the electrolytic caps and "wet" caps?

-Ice

 

[sharkeeper]

You can get more information here.

Cheers!

 

[Xponential]

Ok, thanks for all your help guys. I think I'm gonna get one of the 100GB special editions for now, and maybe another later on for a RAID setup

 

[sharkeeper]

Just make sure that your pair has the same firmware revision!

Cheers!