Specs for External HDD
Pterocarpous
Rosie the Riveter Lives On in CA, USA! New
Hey ya'll,
When outlining recommended specs for a HDD which will be mounted in an external enclosure, I paused when considering on-board cache.
Are the advantages of on-board cache negated by the fact that the HDD will be connected over USB 2.0 (or, at best, firewire). IOW, the USB bus (or firewire) is going to be the bottleneck w/ respect to speed of communication, right?
To that end, what specs would ya'll recommend for an external HDD that will be connected via USB or firewire?
Thankyou in advance!
When outlining recommended specs for a HDD which will be mounted in an external enclosure, I paused when considering on-board cache.
Are the advantages of on-board cache negated by the fact that the HDD will be connected over USB 2.0 (or, at best, firewire). IOW, the USB bus (or firewire) is going to be the bottleneck w/ respect to speed of communication, right?
To that end, what specs would ya'll recommend for an external HDD that will be connected via USB or firewire?
Thankyou in advance!
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Comments
(Still the issue remains, however, whether the increased performance would be lost on a HDD connected over USB or firewire...)
....In addition to the platters, a hard drive has one other small, data holding area called the cache buffer. The cache buffer is made of memory. In the case of a "write," data is transferred from the motherboard to the hard drive's cache buffer. From there, the data is transferred to the drive's platters and written onto tracks. In the case of a "read," data is transferred from the platters to the cache buffer, and then transported to the motherboard. In both cases, the cache buffer serves as a pickup and delivery point for data.
In addition, the cache buffer serves one other purpose. Data that has been accessed recently is also kept in the cache buffer temporarily. If that data happens to be requested again soon, the hard drive has instant access to it. This saves time by eliminating the need to retrieve the data from the platters.
Because researchers found only very minimal performance gains between drives with 2MB buffers and 1MB buffers, they concluded that a larger cache buffer didn't really offer any real world performance benefits. However, that idea changed with the advent of Western Digital's Caviar WD1000BB Special Edition hard drive with 8MB buffer. When comparing the performance of Western Digital's WD1000BB with 2MB buffer and Western Digital's WD1000BB Special Edition with 8MB buffer, researchers from StorageReview.com found that the 8MB drive performed much better than the 2MB drive in a number of tests. This led them to draw the following conclusion:
"An increase in buffer size, properly coupled with a well-conceived caching strategy, yields dramatic improvements in performance." -- Eugene Raw, StorageReview.com, "Revisiting the Caviar WD1000BB and the 'Cuda ATA IV," 10/8/01...
//edit: Yes, you lose performance any time you opt to connect something via USB or firewire that can be connected internally. External bus interfaces have hefty overhead, and a lower priority than the rest of the system's communication buses.
What about 5400 vs 7200? Do you think there'd be any marked difference when connecting the HDD externally?
OkOkOkOkOk The better performer it is.... regardless of where it'll live in the end... Thanx Thrax (I'm off t' eat my hat now....)