Article: AMD's Mobile Strategy
By: EduardoS (no.delete@this.spam.com), December 20, 2011 7:51 pm
Room: Moderated Discussions
Seni (seniike@hotmail.com) on 12/20/11 wrote:
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>This already exists, but hybrid drives are neither as cheap, nor as fast as you
>expect. The Momentus XT, for example, is costing like $100 more than a normal drive,
>and performs more like a slightly faster normal drive, but is nowhere close to the speed of the SSDs.
It costs so much because is the only in the market so Seagate put a higher margin...
It doesn't actually costs (to Seagate) that much.
>If you only have 1-2 NAND chips to keep it cheap, the cache miss rate will be too
>high and peformance will be mostly HD-like.
Momentus XT isn't slow because of high miss rate, it is slow because only features a read cache, nowadays PCs have a big amount of RAM wich is already used as a read cache, writes (wich is the most important for the cache to speed up) aren't served by this drive, that's what I said in my first post, the lack of a decent low-end hardware implementation.
>And with a hybrid drive, not only do you have to pay extra on for the NAND chips,
>you also have to pay extra for the flash-facing side of the controller, which now
>needs its own cores and high-pincount bus. So there's an unavoidable floor cost
>there too. It's a bad deal to pay both floor costs instead of one.
This cost is near zero per device, there is a quite big development costs in both the firmware and controller but can be diluted by a high volume of sales.
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>This already exists, but hybrid drives are neither as cheap, nor as fast as you
>expect. The Momentus XT, for example, is costing like $100 more than a normal drive,
>and performs more like a slightly faster normal drive, but is nowhere close to the speed of the SSDs.
It costs so much because is the only in the market so Seagate put a higher margin...
It doesn't actually costs (to Seagate) that much.
>If you only have 1-2 NAND chips to keep it cheap, the cache miss rate will be too
>high and peformance will be mostly HD-like.
Momentus XT isn't slow because of high miss rate, it is slow because only features a read cache, nowadays PCs have a big amount of RAM wich is already used as a read cache, writes (wich is the most important for the cache to speed up) aren't served by this drive, that's what I said in my first post, the lack of a decent low-end hardware implementation.
>And with a hybrid drive, not only do you have to pay extra on for the NAND chips,
>you also have to pay extra for the flash-facing side of the controller, which now
>needs its own cores and high-pincount bus. So there's an unavoidable floor cost
>there too. It's a bad deal to pay both floor costs instead of one.
This cost is near zero per device, there is a quite big development costs in both the firmware and controller but can be diluted by a high volume of sales.
