Seagate Announces First Hybrid Hard Drive 243
writertype writes "Today, Seagate announced about a dozen new products, including its first hybrid laptop hard drive that includes a 256-Mbyte flash chip to save power and speed up the time a notebook recovers from hibernation. Interestingly, the new Momentus 5400 PSD has also exceeded earlier estimates of hybrid hard-drive performance, which said that such drives would add an extra hour to the typical battery life of a notebook PC."
Re:Will it work? (Score:5, Informative)
Re:What about maximum read/writes for flash? (Score:5, Informative)
It's unlimited reads, but limited writes, so assuming you're using it to store OS code, the limited writes probably won't be a major problem. The limitation is usually in the low millions as well.
Re:Call me a cretin, but... (Score:3, Informative)
What's the difference between a 'hybrid' drive and a drive with a really big cache?
Cache is volatile, flash memory in a hybrid drive isn't. Thus a hybrid drive could save time when you boot, while a large cache won't.
MirrorDot to the rescue! (Score:2, Informative)
http://mirrordot.org/stories/838dd483f468b1c95ac0
Extreme Tech:
http://mirrordot.org/stories/c6b3da4e4e2b800ddf83
Re:What about maximum read/writes for flash? (Score:4, Informative)
Re:What about maximum read/writes for flash? (Score:4, Informative)
Re:lifetime of flash? (Score:5, Informative)
Since Seagate is already defect managing the disk with their firmware, I don't see it being a big challange to have it defect manage the flash as well.
Re:Will it work? (Score:3, Informative)
Re:Will it work? (Score:2, Informative)
On 2000 or XP, the drive will act like a normal drive, albeit with more cache.
It's been done... (Score:3, Informative)
Also, with a fair amount of memory on a laptop and a good filesystem (or Laptop Mode on Linux), you don't need this Flash device to avoid using the disk. Problem is, I've never really gotten it to cache much of the music, although it will avoid writing until it has to, even if I "save" -- which is fine, because the OS can be pretty stable, and a laptop has built-in battery backup, and I can always run "sync". Now, if only I had Linux running on my Powerbook... see, HFS+ does write to disk as soon as it can, which is good for saving data, but bad for saving battery.
Compact Flash 'wearout' (Score:1, Informative)
But consider: 100k write duty-cycle, over a 3 year period, is an update rate of about 90 seconds. That means it's probably OK for user data, but clearly not OK for swap or for system usage such as inode tables for the file system... At 1m duty cycle, that goes down to 9 seconds, which is getting into the ballpark for system kinds of writes (e.g. inode updates for the file system), but it's still not there for swap.
But the underlying problem I'm having is recovery from an error. My guess is that you have to 'write then read' to verify that you have NOT hit the error, and that the probability of the read failing is much less than the probability of the write failing. (And I believe that reading is much more reliable than writing, so that's probably av valid assumption.)
What you then need is a recovery strategy for a failed 'write location'. I guess you could use current failed sector techniques.
So I think this is a cool idea, but I still have some questions about the end-to-end performance and reliability.
dave
Re:Will it work? (Score:3, Informative)
Tasks that require knowledge of what data means without cooperation from the software generating the IO are difficult or impossible to do in a device driver depending on the task. It would be hard, where hard is a relative term in the context of software raid being easy, to accelerate hibernation in a block device driver. It would be impossible to do it well.
Yes, I write storage device drivers for a living, and have personally implemented software RAID and various types of virtualization and multi-pathing in device drivers.