Hybrid Seagate Hard Drive Has Performance Issues

EconolineCrush writes "The launch of Seagate's Momentus XT hard drive was discussed here last week, and for good reason. While not the first hybrid hard drive on the market, the XT is the only one that sheds the Windows ReadyDrive scheme for an OS-independent approach Seagate calls Adaptive Memory. While early coverage of the XT was largely positive, more detailed analysis reveals a number of performance issues, including poor sequential read throughput and an apparent problem with command queuing. In a number of tests, the XT is actually slower than Seagate's year-old Momentus 7200.4, a drive that costs $40 less."

Comments

Re:Well

[Aeternitas827]

This is why I hesitate to be an early adopter of new technology. There's always real-world conditions that occur when a wider sample size comes available (i.e., the Release to Market) than can be reproduced in a lab during testing--and that's true of virtually ANY product. While the problems generally are fixable, it's a pain in the rear to deal with them in the interim. I'll let others be the guinea pigs, thank you very much.

That's life on the Bleeding Edge

[toygeek]

Does anyone not remember the growing pains of previous technologies? Its not like this has never happened before. $Vendor releases $Product that does not meet $Expectations, charges a premium for it, and then fixes it later. Intel put out a whole slew of processors that couldn't even do proper math!

So, if you're going to live life on the edge of the newest technology, this kind of thing is to be expected. Anybody with higher expectations should stick to last years technology and get the best of *that* instead of the newest $uberware to come out.

Re:That's life on the Bleeding Edge

[Aeternitas827]

Anybody with higher expectations should stick to last years technology and get the best of *that* instead of the newest $uberware to come out.

I take that to an extreme; the PC I'm using now is about 5 years old, has no real scalability at this point, but it still works great (especially when I got rid of the Windows user who was using it, and swapped it to Ubuntu) for my purposes. Yeah, it'd be nice to have something nice and shiny and new, but it's not worth the goddam headache.

Re:That's life on the Bleeding Edge

[Anonymous Coward]

Absolutely. For a few years when somewhat-affordable consumer SSDs were entering the market, many of them were total shit, and even the good ones were having firmware upgrades released for them.

Re:That's life on the Bleeding Edge

[toygeek]

I understand that completely. But, when I built my new PC this year, I bought the best of 1-2 year old technology. I'm not a gamer so I didn't need the best of the best, just something fast. Its stable, has no issues, and just works the way it is supposed to.

Re:Well

[Anonymous Coward]

"Just firmware" - don't we remember the fiasco from last year... and their inability to handle it properly.

Re:expected behaviour

[twisteddk]

While I dont share your views on the technology. I do agree that this is expected behavior from a hybrid drive. I have yet to see a hybrid drive that actually does perform significantly better than a normal drive. And that just isn't happening yet.

I'm uncertain if this is because of a poor design, bad queueing, or other issues. But the very BEST hybrid I've seen performs only a couple of percent better than a normal drive, and then not even across the board, but only in specific tests.

Hybrid drives have a long way to go before they become my first choice. But at least you now have an entry level pricing on some of them, which is more than I can say for the full SSDs.

Re:Why Can't It Just Act As Write-Back Cache?

[scharman]

(a.) volatile memory is cheap for the amount needed for only the cache search (all it has to store is maybe 16 bytes per sector which is tiny). The ram cache is a trivial amount of the cost compared to the flash memory which is where your sectors are being stored.
(b.) re-read what I've listed above - I'm not suggesting you remove the OS tier of disk caching.
(c.) a fully associative algorithm is trivial in complexity in contrast to their 'adaptive' algorithms. A CS101 undergrad could implement a reasonable implementation in a hour. This is trivial stuff.

The OS is awful at write-back as if the power fails you've lost state. The benefit of a hybrid drive is that the flash is non-volatile. Writing to the flash ram is cheap. Writing to the disk is expensive. You get the best of both worlds with a flash based write-back cache.

The benefit of flash is it's cheaper than RAM so you can have more of it whilst being far faster than mechanical. Having a 32 or 64 GB flash hybrid drive provides sufficient cache to only rarely need to write back to the disk for most user operations whilst not forcing a 'system' and 'data drive'. As far as the system is concerned, it's just presented as one very fast 2 TB drive (or whatever).

The only time the system will slow down is when you begin to strip the cache which is perfectly reasonable as it means you've exhausted the flash capacity. For 99.999% of usage situations, this will never occur and it will feel just like a very very quick 2 TB flash drive.