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Will C · Aug 4, 2006, 10:38 AM

I know this is bit more of a general hardware question, but as it relates to my eMac (1.25GHz, 1.25GB RAM) I thought I'd post it here - if anyone thinks there is better forum, please say.

If I get a replacment drive, how much difference in performance will I notice between a drive with a 16MB cache and a similar one with an 8MB cache on a G4 machine like mine with Panther. Admittedly I mostly surf and email, but I also do some basic video and audio editing from time to time. Also, if I was to put it in a FW400 case, would there be much difference in speed?

The price difference is a couple of rounds of drinks in London, so maybe I should not be worrying but I don't like paying for something I don't need.

Cheers

Will

jamil5454 · Aug 4, 2006, 11:39 AM

Make sure it is a Parallel ATA drive and not Serial ATA. 16Mb will be faster than 8Mb, especially in small file writes and accesses. When copying large files or streams from the disk, however, the difference will be nil.

Will C · 11:59 AM

Thanks, I was aware of the PATA aspect, but the small files thing makes sense - I have also just realised the stock drive I currently have is only 2MB cache so even just going to 8MB will help.

tooki · Aug 9, 2006, 12:30 AM

Honestly, drive cache size differences make no difference in real-world performance.

tooki

Will C · Aug 9, 2006, 08:16 AM

Originally Posted by tooki

Honestly, drive cache size differences make no difference in real-world performance.

tooki

So why do the manufacturers bother?

Will C · Aug 9, 2006, 08:34 AM

Double post - sorry

iREZ · Aug 9, 2006, 11:34 AM

Originally Posted by Will C

So why do the manufacturers bother?

i would guess marketing. ive noticed no difference between the two, but heck...what do i know.

ghporter · Aug 9, 2006, 11:34 AM

They bother because in SERVER applications, it CAN make a difference. And of course it's another number they can put on the box to get people to say "hey, this must be better because it has a bigger number!"

Platter rotational speed very noticably affects drive performance (i.e. 7200 RPM drives of the same "access speed" metric outperform 5400 RPM drives, which in turn blow 4200 RPM drives out of the water). But the only time you'll see a noticable improvement in performance due to a huge cache is if you're frequently accessing huge amounts of data.

P · Aug 9, 2006, 12:13 PM

Note that bigger caches mean more heat. Make sure that you're not overheating your computer with a big cache that doesn't help the speed.

mduell · Aug 9, 2006, 04:42 PM

Originally Posted by P

Note that bigger caches mean more heat. Make sure that you're not overheating your computer with a big cache that doesn't help the speed.

I have a hard time believing that an extra 8MB DRAM is going to produce much heat.

ghporter · Aug 9, 2006, 05:30 PM

Originally Posted by mduell

I have a hard time believing that an extra 8MB DRAM is going to produce much heat.

Better stated than my reaction: "HUH???"

Actually, a fair-sized cache can theoretically reduce drive temperatures by reducing accesses to the platters themselves. But this is only when all the needed data is cached. In other words, in situations where cache size really matters, the cache does more than just reduce access time. But for the normal desktop/laptop user, that's still not a player.

tooki · Aug 10, 2006, 10:55 AM

Originally Posted by Will C

So why do the manufacturers bother?

Because RAM keeps getting cheaper, so drive manufacturers can keep increasing the cache amount for marketing purposes without increasing drive cost.

There are, as ghporter said, some server apps that benefit from big caches.

On the desktop, you'll never notice. A faster drive will do more.

There's no way a tiny cache will make a lot of heat. The drive mechanics make heat. RAM hardly creates heat at all. And since newer memory uses less power than old memory, a current 8MB cache probably uses no more power (and thus dissipates no more heat) than 2MB from 5 years ago.

tooki

P · Aug 10, 2006, 03:41 PM

I'll admit that my statement about the drive cache is an old rule of thumb from Wayback, and it may be that with current RAM standards, the extra heat is negligible.

Tomchu · Aug 10, 2006, 03:44 PM

The thing about 16 MB caches is that going from 8 MB to 16 MB requires some algorithm changes in order to properly utilize that 16 MB. As far as I know, Western Digital is currently the only company with a 16 MB cache SATA/IDE drive that has properly tuned the firmware on the drive to utilize the cache. Maxtor added 16 MB just for marketing purposes (and to meet WD's standard).