New AT article on 2nd gen Momentus XT

[bryanW1995]

http://www.anandtech.com/show/5160/seagate-2nd-generation-momentus-xt-750gb-hybrid-hdd-review

Also has a nice 11 minute video review by Anand at the bottom of pg 1.

 

[Coup27]

It's an interesting option but I do not really understand how enabling write caching will achieve much.

For the average user, writes are not predictable. You will install your OS, install your drivers, OS updates, programs, games, and copy over whatever data you want on that disk. All of those operations are one time writes and won't be cached. After that writes will mainly be more OS updates, more program installs and updating data. I don't get how write caching will work.

 

[monkeydelmagico]

I find this type of hybrid interesting. The price seems good too.

 

[allthatisman]

It's $239 on Newegg + shipping... why on Earth would the average user need 750gb of space on an OS/App drive?? For the same price you can almost get a 160gb Intel 320 SSD... I have a bunch of games and all my apps installed on mine, and still have plenty of space left over... I tried on two seperate instances to use the 500gb XT to it's fullest, and I was never satisfied with the level of performance or consistency... It was loud and the APM was way too agressive.

This drive has priced itself out of any serious contention, especially since we're seeing the larger SSD's become more affordable.

 

[Concillian]

It's an interesting option but I do not really understand how enabling write caching will achieve much.

For the average user, writes are not predictable. You will install your OS, install your drivers, OS updates, programs, games, and copy over whatever data you want on that disk. All of those operations are one time writes and won't be cached. After that writes will mainly be more OS updates, more program installs and updating data. I don't get how write caching will work.

Using NAND as a write cache allows for safe deferred write to the platters.

Keep a small area of NAND available for Writing.
Use this space for small size writes that will be mostly seeking time. The data is safely written to the NAND in the event of power issue, and they are deferred until the drive is done reading so it can dedicate seeks to reads for fastest read performance.

Writes in this case are small enough that you don't need a lot of NAND to really gain performance. 1 GB is a LOT of cache to be used like this, as most real world writing events are pretty small when you do something like launch an application or load a game level. There are definitely writes though, and small file size writes can really muck with performance due to seeks.

You can test how it affects performance yourself by using fancycache and a RAM cache with deferred write. With 16 GB RAM and dedicating 8GB of that to caching, you can somewhat emulate a hybrid drive... if you re-load the same application a few times in a single boot. You obviously cannot carry this advantage across multiple boots, since the RAM is volatile, but it will allow experimentation to see how a hybrid drive would improve performance.

My experience with my Intel 320 and on a hard drive + fancy cache is that read caching is good, and you can get significant benefit, but adding deferred writes, you can truly get that real SSD-like feeling, at least for stuff which fits in the cahce (an 8GB cache seems to be large enough for what I do, which is mostly just browse and run a few games. With the occasional photo editing session.

 

[greenhawk]

I don't get how write caching will work.

as mentioned, it just allows for better reliability in case of power issues as the SSD will take the data. Current systems just use RAM to cache some writes, but that performance is at the cost of failed writes.

Writing to a SSD would hopfully allow the drive to recover from bad writes as the data is still in the SSD part. So if a bad cluster will not take the write, the drive has the data to try as as often as it wants/needs.

Only one situation, but as you mentioned, generally writing cache does not help performance on a large scale, just in the small number of situations.

 

[greenhawk]

why on Earth would the average user need 750gb of space on an OS/App drive??

people that are considered normal users that only like having one drive letter or have a laptop and still want space (as carting external drives is too much of a hassel).

I would get something similar for my parents or siblings, but for a nerd/power user, they would just go for the read deal SSD instead

 

[bryanW1995]

With 256gb drives going for less than $1/gb AR on BF, it's hard to justify a momentus at $249 imho. It really needs to be less than $200. Now, if your laptop only has one drive bay and/or don't want to remove your cd drive, a hybrid like this that holds 750gb of data can be extremely useful.

 

[rsutoratosu]

Caching is King !

Cache is everywhere, your processor has cache, drive has cache, video cards, etc..

I'm in the process of implementing storage system using Nexenta and we're using two ocz revo ssd pcie as caching drives. This will sit in front of array of sas 15k down to sas 7.2k drives. The key is the same, try to make the system look faster than it is using caching.

 

[Coup27]

...

A good point well made.

 

[monkeydelmagico]

Caching is King !

Cache is everywhere, your processor has cache, drive has cache, video cards, etc..

I'm in the process of implementing storage system using Nexenta and we're using two ocz revo ssd pcie as caching drives. This will sit in front of array of sas 15k down to sas 7.2k drives. The key is the same, try to make the system look faster than it is using caching.

That sir is freakin brilliant. :thumbsup: I'd be curious to see what type of longevity you get out of the revo drives