Disk spin rate vs sshd cash

[TBUDWEY]

When buying a hybrid drive with a choice between a drive with a 7200 spin and 32MB cash and a drive with 5400 spin and a 64 MB cash how would you decide on one or the other?

 

[kanewolf]

32MB isn't enough difference to overcome the performance penalty of 5400RPM in my opinion. But with the prices of real SSDs falling so much, hybrid drives will soon become extinct.

 

[TBUDWEY]

32MB isn't enough difference to overcome the performance penalty of 5400RPM in my opinion. But with the prices of real SSDs falling so much, hybrid drives will soon become extinct.

There are a lot of drives on the market that have cache memory but are not advertised as being a hybrid drive. Are they actually a hybrid drive or is there something else to a hybrid that I don’t understand?

 

[kanewolf]

A hybrid drive has FLASH memory cache rather than DRAM cache. Anything written to the DRAM cache still has to be written to disk or read from disk into the DRAM. FLASH cache disks can permanently keep things in cache since there is no danger of losing information.

 

[TBUDWEY]

A hybrid drive has FLASH memory cache rather than DRAM cache. Anything written to the DRAM cache still has to be written to disk or read from disk into the DRAM. FLASH cache disks can permanently keep things in cache since there is no danger of losing information.

That's a relay good point. So if the drive dose not advertise itself as a SSHD drive the cache is DRAM not FLASH?

 

[Someone Somewhere]

Yup.

SSHDs also normally have a couple of gigabytes of cache rather than a few tens of MB.

I'm not certain, but I think SSHDs still have DRAM cache, it's just that it's in addition to the flash cache.