Hybrid drive spinup

[storageinventor]

Does anyone know if a hard drive must be spinning at its full rate before the read/write head can function correctly?

One of the disadvantages listed for hybrid hard drives is that lots of power (and wear and tear) is needed during the spin-up of the drive when a read request comes in for a block that is not in the flash memory buffer.

If a read request comes in for a single block located on a platter surface, how fast does the motor have to spin before the block can be read?

It seems to me that a hybrid drive could save a lot of power by spinning at just a few hundred RPM. If 90% of the requests hit the flash memory cache and only 10% require a spinning platter, couldn't you get about the same throughput on a 720 RPM hybrid drive as a plain old 7200 RPM non-hybrid drive?

 

[cjl]

It has to be at full speed before it will read anything.

 

[shadowthor]

if you want to save power, you can get a ssd.

 

[storageinventor]

What if you want to save power but still want 320 GB or more of data? Last I checked SSD drives are still about ten times the $/GB as a hard drive.

 

[cjl]

I wouldn't slow it down at all. More data than you might think is still read off of the disk on a hybrid, and that would slow down the overall performance immensely. As for power savings, hard drives are actually quite good at it. They already have extensive power saving modes, without even needing to spin down in many cases. Because of this, they are already only a minimal factor in the overall system battery life (unless you have a really low power system).