How much faster is 32mb cache compared to 8mb?

[Rick James]

Both 7200rpm drives?

[Quigsby]

In what context? Read, Write, Access?

A cache is memory which can be read much faster than moving a mechanical piece out to a platter. This allows items that are accessed frequently (say, common items in a video game like a graphic) to be returned much faster than the mechanical call.

If you were to transfer data from one hard drive to another, I don't think you'd see any difference - but I don't have data to back that up. :)

[Particle]

It largely depends on who made the drive. Western Digital's caching system tends to be superior to anyone else's. I'd rather have a 16MB WD than a 32MB Generic Company X. In any case though, the cache's impact on performance is likely to be very small. Your OS will do all of the smart work when it comes to caching data that it thinks you'll want to use frequently, and it'll be able to cache a lot more than disk cache can store.

[Old Thrashbarg]

On-drive cache size only makes a difference in two things: burst speeds and marketing. The former doesn't really matter much.

People don't generally seem to understand how the caching works. It's just a small buffer between the interface and the media that allows a bit of leeway for the bus not to have to wait on the main storage media and vice versa. Neither the drive nor the bus can do both reads and writes at the same time so if the drive is reading something, the bus has to wait before it can write something.

But, modern OSes do their own write caching, which is much more intelligent in how it caches, and it has much more memory to work with as well. And when the data stream is already somewhat optimized, adding a couple more MB cache to the HD itself won't do much. Also, the cache is only effective in small, random writes anyway... for larger sequential transfers it won't make a lick of difference.

(I should point out that the cache on SCSI RAID controllers is a different case, but that's not the subject at hand.)

[KTE]

I own, and have been through plenty of Western Digital 16MB and 8MB drives. Partly due to the nature of my work. I generally stick to Western Digital for many reasons based on my experiences and have ditched Seagate for the Desktop. Between both, Western Digital Caviar Blue at 8MB and 16MB cache, the difference was negligible in synthetics and didn't exist in real workloads (i.e. file create, file copy, file delete, file read, etc).

The WD Caviar Black at 32MB cache performs faster overall than the WD Caviar Blue anyway, so I can't say whether its solely due to a doubling of cache or otherwise in the most certain terms, but I doubt the cache will offer much benefit knowing their workings.

[wingman99]

It wont make any difference in speed.

[trents]

I think the only thing in conventional sata or ide hard drives that have much impact at all in performance is platter rpm. Whenever they have gone up a notch in rpms, like from 5400 to 7200 or 7200 to 10,000 then you get a meaningful performance increase.

[Old Thrashbarg]

I think the only thing in conventional sata or ide hard drives that have much impact at all in performance is platter rpm.

Platter density is really as much or more important as RPM. Both have similar effects... getting more data passing under the heads in a certain amount of time. My 5400RPM Samsung 1TB drive is as fast as an older 7200RPM drive, save for maybe a couple ms access times, due to its 320GB platters, and the WD 640GB 7200RPM drives are, for most purposes, as fast as the older 10K RPM Raptors.

[wingman99]

Platter density is really as much or more important as RPM. Both have similar effects... getting more data passing under the heads in a certain amount of time. My 5400RPM Samsung 1TB drive is as fast as an older 7200RPM drive, save for maybe a couple ms access times, due to its 320GB platters, and the WD 640GB 7200RPM drives are, for most purposes, as fast as the older 10K RPM Raptors.+1 how true.:D

[Rick James]

Thanks guys. I went with an SSD over as traditional hard drive :)