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External RAM cache for SSD

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December 19, 2009 4:47:36 PM

I am putting together a high performance system and looking for any reasonable speed tweaks. Just waiting for the video card to be delivered!

"Back in the day" there were software solutions that would use system memory to augment the slow hard drives. Seems to me that in the current SSD market that a RAM based, external card, with a GB or two of fast memory would take care of both the SSD aging and the (relatively) slow write speeds associated with SSDs. Are there any such devices/reviews out there? My four hours of Google, Bing and HW sites totally unsuccessful in finding anything.

17-975 +20%
2x 128GB Torqz SSDs (Raid 0)
1.5 TB Caviar Data Drive
P6X58D MB
12 GB DDR3-1333 memory
HD5970 Graphics
X-Fi Titanium Fatal1ty Audio
ATSC 840 Case / Hyper 212 Plus cooler

Michael

More about : external ram cache ssd

a c 415 G Storage
December 19, 2009 6:40:52 PM

Windows itself uses RAM as a cache and does "lazy writes" to any drive. The only other solution you're likely to find is a RAID card with RAM cache. I'm really not sure that it would make that much difference - unless you actually use the RAID card for a RAID-5 array, in which case the RAM cache helps a lot to eliminate the very poor write performance of RAID-5 sets.

What are you going to be using the SSD for? Sequential write performance is almost irrelevant for an OS / application drive. The only time it really becomes significant is if you're using it to store large data files that you rewrite a lot - not a typical use for most folks.
December 19, 2009 7:47:52 PM

sminlal said:
Windows itself uses RAM as a cache and does "lazy writes" to any drive. The only other solution you're likely to find is a RAID card with RAM cache. I'm really not sure that it would make that much difference - unless you actually use the RAID card for a RAID-5 array, in which case the RAM cache helps a lot to eliminate the very poor write performance of RAID-5 sets.

What are you going to be using the SSD for? Sequential write performance is almost irrelevant for an OS / application drive. The only time it really becomes significant is if you're using it to store large data files that you rewrite a lot - not a typical use for most folks.


Thanks for the input. My primary use is for the OS (WIN7U). I also do video editing which has a lot of disk activity (at least on my current 2GB, slower, system). Are there RAID controllers that have large amounts of memory? I couldn't find any larger than 64 MB.
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a c 105 G Storage
December 19, 2009 8:10:30 PM

If all you want is 4 Ghz, that can be done on a i7 920 easily enough for some $$ savings.

Unless you need the 12 GB, 6 GB is generally faster....and you can buy memory w/ better coolers. For 12 GB, I'd grab the mushkin 998691 w/ w/ 6-7-6-18 timings before they disappear again.

http://www.newegg.com/Product/Product.aspx?Item=N82E168...

For the case, since you seem to be drawn to CM, I'd like to see you in the CoolerMaster HAF932 w/ a Corsair HX-850. better yet even the Antec 1200 w/ CP-850 (or SG-850) ... yes if you don't dig LED's can be turned off

Might wanna consider on of these given your storage comments.

http://www.newegg.com/Product/Product.aspx?Item=N82E168...

Finally, would like to see you in a better cooler. Newegg is outta stock so.....

(1) http://www.frozencpu.com/products/8807/cpu-pro-01/Proli...
(1) http://www.frozencpu.com/products/7038/thr-41/Innovatio...
(2) http://www.frozencpu.com/products/10026/fan-639/Scythe_...
(1) http://www.frozencpu.com/products/8418/cab-150/FrozenCP...
December 19, 2009 8:33:41 PM

Since all parts sitting in my work shop, waiting on the video card, I can't impliment some of the excellent input :wahoo: 

Jack: The +20% OC is just a conservative estimate, I'll let stability/temperature testing show me the real numbers. I will post some benchmarks when the parts become a PC. The memory size is because of large scale video processing, the speed because I want to play some games.
I looked at a lot of coolers and the CM got really good reports for both performance and value (Typical - http://www.*****/forum/hardware-canucks-reviews/19383-cooler-master-hyper-212-plus-cpu-cooler-review-10.html).
December 19, 2009 8:41:29 PM

the last resort said:
I found some on Newegg that has the option for plugging in DDR2 sticks for cache. Heres one with 4GB cache. VERY PRICEY.

http://www.newegg.com/Product/Product.aspx?Item=N82E168...


OUCH: Now that I know they exist - any (quantifiable) ideas on performance improvement?
Thanks for the input
a c 415 G Storage
December 19, 2009 11:24:26 PM

mkperrett said:
Thanks for the input. My primary use is for the OS (WIN7U). I also do video editing which has a lot of disk activity.
The reason you pay extra for an SSD is because they have very fast random I/O capability. You don't really need that for video editing, and the large size of most video files mean that SSDs are very pricey for that kind of use. You're may be just as well off keeping only the OS and the program files on the SSD and putting the video files on a larger, reasonably fast hard drive.

But everyone's different, so experiment a bit to see what works best for you.
December 20, 2009 9:00:07 PM

Everyone's different, but I would also take a mechanical disk for video editing - or better several disks in Raid-0. One of the few uses where Raid-0 is still sensible.

Wear isn't an issue on Flash disks.

Decent SSD already have Ram onboard to cope for big write pages. Choose the SSD properly, instead of looking for trouble with a composite solution.

You get significant data, including write and small files, through IOMeter (not obvious to use nor to interpret) and CrystalDiskMark (much easier). By googling these words together with the SSD, you get usable information about SSD behaviour in real life. You may also compare with a mechanical disk.

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a c 154 G Storage
December 21, 2009 1:31:14 AM
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A SSD reads data very well. The underlying flash storage today does not write very well. It is best suited as an OS drive which does small random reads and writes.

For your editing process, a large cache will defer the time to do the writes, but a large file must eventually make it's way to the external store. Unless most of your output file can be contained in the cache, it will not help.

If your files can be contained within 10gb of your 12gb, then a ramdisk program would be the fastest. It emulates hard drive activity in ram. 24gb is possible but expensive.

My best suggestion for large file editing is to use two conventional hard drives, the faster the better. Put your input data on one drive and the output on the other. That will reduce the arm contention that you would have if both files are on the same drive. If you have 4 drives, you could use two raid-0 arrays to good effect.
The fastest hard drives will be the newer 1tb+ drives which are denser and transfer more data per revolution.
December 23, 2009 5:18:36 PM

Write throughput is good for many SSD! Look at the figures.

It's the write latency which is bad, especially with MLC Flash.

But then, manufacturers write huge Flash pages at once to obtain the desired write throughput.

So a Ram cache IS the real solution to get good write performance of an SSD, allowing very fast write latency and keeping the good write throughput obtained by paralleling.

What I doubt (or rather: I disbelieve) is that a separate Ram can improve anything, since it won't work properly together with the Flash controller. The real solution is a recent SSD which integrates said Ram and whose controller is aware of the Ram, taking full advantage of it.

Especially, the wear-levelling algorithm has the added advantage of grouping small data, like single sectors, within big write pages, so that small writes don't suffer too much from write latency, as they share on single latency.
December 30, 2009 4:01:38 AM

Everybody: Thanks for all the input.

What I walk away from all of this is that there is only a single method to improve the write time of the SSD – that is a Raid controller with large (estimate 4 to 8 GB) RAM cache. Special thanks to SMINLAL, GEOFELT and POINTERVOID for their knowledgeable information.

Given the huge cost for a minimum noticeable improvement; my plan is to do nothing (at first)! I will benchmark the system, work with the applications for awhile and see if there is a need for any system improvement. I now believe that the system as described in the first post (STILL waiting for the HD5970 video card!) will perform most anything I can think of admirably, and will until the next generation of hardware comes out (actually I always skip at least one generation).

Thanks again for taking the time,

Michael
!