SSD portion of hybrid drives

[momboso]

I thought the SSD portion of a hybrid drive was generally from 4-128 GB. Why are they being listed all over with statements about cache in MB (three orders of magnitude smaller)? If that is something different, why is the SSD size not listed?

 

[Someone Somewhere]

A standard HDD usually has a cache of 8-64MB. A Hybrid HDD usually has a NAND cache in the tens of GB.

You may be mixing up your acronyms.

 

[momboso]

Ok, cache is not NAND cache, but I saw some hybrid drives listed with 32 and 64 MB cache, and no size spec for the SSD portion. Do the hybrids have two cache types, and wouldn't the SSD NAND cache be most important to list?

 

[Someone Somewhere]

They have both RAM and NAND cache - the RAM is stuff ready to go from/to the SATA port, the NAND is long-term storage.

What drive? Link?

 

[momboso]

http://www.amazon.com/s?ie=UTF8&keywords=hybrid%20hard%20drives&page=1&rh=i%3Aaps%2Ck%3Ahybrid%20hard%20drives

http://www.newegg.com/Product/ProductList.aspx?Submit=ENE&DEPA=0&Order=BESTMATCH&Description=hybrid+hard+drive&N=-1&isNodeId=1

Newegg lists one; most listings state the RAM cache but not the NAND cache/SSD size. What is up with that?

 

[Someone Somewhere]

Interesting - my guess is a combination of people looking for cache sizes because it's what they've always done, and Seagate/WD not wanting to be compared in respect to the exact amount of NAND. Probably only 4GB.

 

[popatim]

The St1000lm014 has 8gb nand. There are a few models that have 32gb.
http://www.seagate.com/files/www-content/product-content/momentus-fam/momentus-xt/laptop-sshd/en-us/docs/laptop-sshd-datasheet-1784-1-1302-us.pdf

 

[momboso]

Thanks for the doc. Any pointers to the 32Gb NAND drives?

I seem to remember some discussion re 64Gb NAND hybrid drives and larger (Don't remember where). Maybe someone will design a routine to log, analyze, and profile caching patterns. But, until various user groups are sampled, some will buy too little NAND, and others will buy more than they need.

 

[momboso]

" Any pointers to the 32Gb NAND drives? "

Anyone using a hybrid drive? Seagate Momentus drives are apparently popular lately, but what about the Western Digital models (different system, I read)?

I am thinking about a 500 GB drive: What model is recommended (brand and #)? What size is the NAND ram?

Regarding Seagate switching to 5400 rpm for the spinning portion: Do they choose that because it is faster to spin up to 5400 rpm compared with 7200 rpm (while letting the NAND portion do the speedy caching)?

If one tends to save open files frequently, in case the machine or program crashes, will this significantly use up the SSD life (using write cycles)? Imagine working frequently in some spreaadsheet files and saving frequently.

I like the Seagate strategy to encourage letting the firmware manage what and when goes to the HDD and what and when goes to the SSD. It sounds like WD will allow (require?) more interaction, but it seems best to use some automatically tuning algorithm. Any thoughts on this?

 

[popatim]

ST1000LX003
ST750LX006
Both had 32gb nand but really, at that much nand just get the readycache ssd and use whatever hdd you want.
http://www.newegg.com/Product/Product.aspx?Item=N82E16820171667