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Samsung Rapid Mode?

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Pepi93

Member
Joined
Jul 12, 2002
I'm curious how accurate or valid this "Rapid Mode" actually is? You can only have it enabled on your OS or only on one drive? That's fine. What puzzles me is the read/write values that both magician and crystaldiskmark report...

Rapid Mode is enabled on the 250gb.

Should I even be using Rapid Mode?


250gb_Rapid_Mode_Enabled.jpg 500gb_No_Rapid_Mode.jpg
 

ATMINSIDE

Sim Racing Aficionado Co-Owner
Joined
Jun 28, 2012
Not sure what you're asking by "accurate" or "valid", but RAPID mode is a form of RAM caching for the SSD.
Being as such, RAM is faster than an SSD by multiple orders of magnitude, which is why you see the results in the screenshots.
 
OP
Pepi93

Pepi93

Member
Joined
Jul 12, 2002
Not sure what I'm asking either. :)

From what I'm reading it seems it's not a good idea to use Rapid Mode? People are experience all types of problems though I don't think this applies to me. All my BSOD's, black screens were NVIDIA/AMD driver/hardware related issues.
 

ATMINSIDE

Sim Racing Aficionado Co-Owner
Joined
Jun 28, 2012
I've used RAPID mode for years, ever since I got my 840 EVO years ago, and have had zero issues with it.
The performance boost is noticeable though, so that's why I kept it enabled.
 

Johnny Lucky

New Member
Joined
Sep 4, 2015
Location
Tucson, AZ
Samsung's Rapid Mode is a variation of a virtual ramdisk. In a virtual ramdisk configuration a portion of the system's DDR memory is used as a cache for the ssd.

Your benchmark results with Rapid Mode enabled are for the system's DDR memory that is used as a ramdisk. The benchamrks with Rapid Mode are not for the ssd. The actual ssd performance remains at the typical 530 to 550 MB/s.

The Rapid Mode benchmarks are high because the DDR system memory perofrms a lot faster than the flash memory used in ssd's.

Ramdisks were originally developed for use with hard disk drives. I first used one way back in 1985 with my first pc. The old hard drives were really slow. I used a Ramdisk with a Seagate 10MB (not GB) hard drive with 120 millisecond access (not nanosecond) that cost $350.00.

A few years ago AMD introduced their own line of DDR memory. AMD included a free copy of DataRam's ramdisk. That generated some interest and several articles were published. There are other companies that also have virtual ramdisk applications. Some are free and some cost a little bit.

Samsung's version is actually a scaled down variation. The company decided to limit the quanity of DDR memory that could be used for a ramdisk. Initially the size of the Ramdisk was limited to 1GB of memory if available and it will not load certain large files into the Ramdisk. Eventually it should be increased to 4GB of system memory if available. Other Ramdisk version do not have such limitations.

The Samsung Rapid Mode benchmarks are a bit deceiving. Technical reviews revealed the actual real world increase in performance is anywhere between 0% and 25% depending on what was loaded into the Ramdisk. The 0% represents brand new data of some type that has never been loaded into the Ramdisk while the 25% represents some type of data that is routinely loaded into the Ramdisk.
 

dyckah

Member
Joined
Jan 9, 2005
I would not use Rapid Mode with 8gb of ram, i found when i did that, i was constantly running out of ram, and getting big lag spikes while gaming.
since upgrading to 16gb of ram, i have not noticed any issues with it!
 

ATMINSIDE

Sim Racing Aficionado Co-Owner
Joined
Jun 28, 2012
I would not use Rapid Mode with 8gb of ram, i found when i did that, i was constantly running out of ram, and getting big lag spikes while gaming.
since upgrading to 16gb of ram, i have not noticed any issues with it!

Pepi has 16GB.
 

Mpegger

Member
Joined
Nov 28, 2001
I only use HDD cacheing, via a SSD and some ram, but even with 32GiB of ram, I'd still skip cacheing a SSD with any ram cache, other then what's built into Windows. Even with 16GiB of ram, in a Windows 7 or higher environment, I'd just leave Rapid Mode disabled, and let the OS manage caching. It'll be more efficient use of your ram then keeping a portion of it tied up 100% of the time.
 
OP
Pepi93

Pepi93

Member
Joined
Jul 12, 2002
I only use HDD cacheing, via a SSD and some ram, but even with 32GiB of ram, I'd still skip cacheing a SSD with any ram cache, other then what's built into Windows. Even with 16GiB of ram, in a Windows 7 or higher environment, I'd just leave Rapid Mode disabled, and let the OS manage caching. It'll be more efficient use of your ram then keeping a portion of it tied up 100% of the time.

This is interesting because I have virtual memory set to 1024mb as suggested by SSD tweak guides. So what you're saying is turn off Rapid Mode but let windows allocate its default virtual memory size? Anyone else have an opinion on this?

Also, I do believe I ran into some issues RAM when having only 8gb of installed memory but no problems since having 16gb.
 

Johnny Lucky

New Member
Joined
Sep 4, 2015
Location
Tucson, AZ
I am not excited about the way Samsung has configured Rapid Mode. Rapid Mode is a scaled down version which should not be compared to full versions available from other vendors. There are many Ramdisk features and options that Samsung does not include.

I see 8GB and 16GB memory has been mentioned. Those are typical consumer capacities. I also understand there are budget considerations.

Enthusiasts are a completely different matter. I am currently working on a case mod project. The project includes an MSI Titanium Z170 motherboard and 64GB of system memory. I'll be using 16GB for the system and 48GB as a Ramdisk. By using a full version I can choose what I want loaded into the Ramdisk. I can have it start automatically when I boot the pc or I can choose which applications and utilities I want to load. For professional work I can choose to load an entire photo editing application, a few extra photo apps, and the raw images I work with. Everything, including rendering, happens instantly.

There is one downside I forgot to mention. It takes a few seconds to load applications and files to the Ramdisk and a few seconds to save the data when finished.

BTW - I purchased my first PC in late 1984. It was an IBM pc with 512Kb (not MB or GB) of memory and the operating system was DOS 2.0. There was no hard drive. The pc came with two 5.25 inch floppy drives. The following summer I read about a company by the name of Seagate that had a 10MB (not GB) hard disk drive with a 120 millisecond (not Nanosecond) access time. I bought one for $350.00. The hard drive worked but it was still slow and it made a lot of noise so I installed my first Ramdisk. It worked with just a few KB of memory.
 

Mpegger

Member
Joined
Nov 28, 2001
This is interesting because I have virtual memory set to 1024mb as suggested by SSD tweak guides. So what you're saying is turn off Rapid Mode but let windows allocate its default virtual memory size? Anyone else have an opinion on this?

Also, I do believe I ran into some issues RAM when having only 8gb of installed memory but no problems since having 16gb.

If you are using anything from Windows 7 or above, the SSD tweak guides for the most part, are no longer applicable (other then moving large data directories to other drives if you require more space). Although, a 1GB page file is just fine with 16GiB or more of system ram, as most individuals would barely max out that amount of ram.

The page file (what you are referring to as virtual memory) should only come into play when you run out of actual space on ram. You say you had issues at 8GiB, which means that you were running enough applications that 8GiB was not enough and would cause the OS to use the pagefile, which is of course, slower then ram. By upgrading to 16GiB, the OS now had 8GiB more of ram available and no longer needed to make use of the page file. Windows 7 and above will automatically use whatever free ram you have available for cache purposes (though its only a "last accessed" algorithm afaik), so you would see speed benefits even without a separate Ram Cache program. The OS can also easily release the ram being used as cache for use by active programs, while a separate Ram Cache program cannot. Whatever ram the Ram Cache program has allocated (say 4GiB worth of ram), will no longer be available for anything else. In essence, with the example I just gave, you would no longer have 16GiB of ram, only 12GiB. If you run enough programs to use up most of that remaining 12GiB of ram, it would again have to use the page file, which of course slows the system down.

We can give you all the opinions we have on this issue, but it boils down to your use and need of your system. What you need to figure out is what is your typical ram usage, as well as what is your max ram usage, on your system. If you feel you have enough spare ram that never gets used, and can give up some of that space for a Ram Cache, by all means, go ahead and do so.

I have 32GiB of ram. The most I've seen of my ram in use is around 24GiB, though typically, I'm around 12-16GiB usage. Even with that much spare ram, I've only given 4GiB to my HDD cache via PrimoCache, as it's smarter as to what it keeps cached in ram then the OS (it uses "most frequently" accessed algorithm as well as other methods). The rest of the ram that is not in use, will be put to use by the OS as cache.
 
OP
Pepi93

Pepi93

Member
Joined
Jul 12, 2002
Thanks Johnny Lucky and Mpegger for explaining this.

Rapid Mode did in fact cache 4gb of my RAM so turned it off for the time being to see if I notice any changes in performance.

My reasoning is that if I don't notice a performance hit for turning rapid mode off, then what's the point in having 4gb of my RAM cached.
 
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JrClocker

AKA: JrMiyagi
Joined
Sep 25, 2015
I am always cautious about using any sort of large disk caching back to a main OS drive. You have a high probability of corruption if you BSOD and the cache has not written to the disk.

I setup a RAM Disk when I am doing heavy simulations. I page the temporary results to the RAM Disk versus a real disk as its lots, lots faster.
 

knoober

Member
Joined
Mar 18, 2015
This sint too big of a ressurection so I hope no one minds...

samm1.PNG
Exibit A: Samsung 850 Evo 120Gb with Rapid Mode enabled

samm2.PNG
Exibit B: A 4gb ramdisk

Ive looked into Ramdisks enough to know that not all are equal and that some are faster than others but this Samsung drive with rapid mode enabled is beating the hell out of my RAM. Thats pretty much cant be...right? Id like some other opinions on this please.


Also in support of Rapid Mode being BS: http://techreport.com/review/25282/a-closer-look-at-rapid-dram-caching-on-the-samsung-840-evo-ssd
I understand that you can find alot of info about rapid mode that says it is good or bad, but this one has lots of cool pictures to go with it :)