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-   -   Ram Cache and Ram Disk, Real world difference? (http://www.hardwarecanucks.com/forum/ram/57604-ram-cache-ram-disk-real-world-difference.html)

BobbyLou October 30, 2012 05:47 AM

Ram Cache and Ram Disk, Real world difference?
 
Obviously in benchmarks and stuff there seems to be a great boost in performance but what is the real world performance be like? If you already have two fast ssd's in raid 0 would you notice a difference?

Chasingu October 30, 2012 07:24 AM

I use RamDisks for games, and besides the annoyance factor of having to move the game over to the ram disk, then move it back when your done, there is noticeable performance boost, in some games. There are some games I can think of that it really doesn't do much. Remember, a RAMDisk is "an SSD with no Wearing Out and around 100x faster" however it is more volatile.

3oh6 October 30, 2012 07:44 AM

Quote:

Originally Posted by Chasingu (Post 667384)
I use RamDisks for games, and besides the annoyance factor of having to move the game over to the ram disk, then move it back when your done, there is noticeable performance boost, in some games. There are some games I can think of that it really doesn't do much. Remember, a RAMDisk is "an SSD with no Wearing Out and around 100x faster" however it is more volatile.

Save yourself the hassle and get something like this: RAMDisk - Software - Server Memory Products & Services - Dataram

It saves an image of your RAMDisk at intervals and shutdown. It then restores the image at startup. Takes a few minutes to boot, but saves the hassle.

@OP I run a RAMDisk for my entire development environment. I'm a web developer and it makes my dev setup almost instantaneous. It really was a night and day difference once I made the switch. Obviously this is pretty specific, but RAMDisks definitely have uses. Often you just have to figure them out for yourself. Other devs that have used my box lose their mind at how responsive it is.

I haven't ever had a RAID 0 with a pair of fast SSD's, so I can't comment on the RAMDisk VS them, but I previously had a 4 drive RAID 0 of 7200's (obviously not SSD's) but it was painfully slow compared to my setup now.

BobbyLou October 30, 2012 08:12 AM

Great!

and what about ram caches?

dandelioneater October 30, 2012 09:03 AM

Quote:

Originally Posted by BobbyLou (Post 667393)
Great!

and what about ram caches?

I think a ram cache would just be regular system memory as it caches files and data that you are using for quicker access by the cpu.

Ardric October 30, 2012 11:57 AM

The trick is called cache preload. If you copy everything from disk to ram before you launch the app, then the app runs completely out of ram. It doesn't matter whether you allocate a fixed ramdisk size and copy the files in, or you simply copy the files to /dev/null and let your automatic buffer cache handle it. Either way works and yields the same speed in the end.

In linux, one can preload a directory into buffer cache by issuing a command like

find mydirectory -print0 | xargs -0 cat >/dev/null

There's probably a Windows equivalent command, but I'm not sure what that might be.

BeaverBender October 30, 2012 12:50 PM

fetch

Chasingu October 30, 2012 04:48 PM

Im cheap, so I use ImDisk, and I made Batch Scripts to automatically transfer the games to and fro. I'm actually going to write a Visual Basic program that will make the disks and archive them, without having to manually run the scripts.

Generic User #2 October 30, 2012 07:06 PM

Quote:

Originally Posted by 3oh6 (Post 667388)
@OP I run a RAMDisk for my entire development environment. I'm a web developer and it makes my dev setup almost instantaneous. It really was a night and day difference once I made the switch. Obviously this is pretty specific, but RAMDisks definitely have uses. Often you just have to figure them out for yourself. Other devs that have used my box lose their mind at how responsive it is.

you wouldn't happen to use visual studio would you? I do .NET web dev for work, but I do alot of desktop stuff in my spare time as well.

were you using an SSD before?

I'm thinking that since I rarely turn off my system anyways, a RAM drive would be nice, since VS, Office, and browsers are the only things that aren't instant on my M4. Did you ever have any data corruption/crashes related to your RAM drive?

3oh6 October 30, 2012 08:15 PM

Quote:

Originally Posted by Generic User #2 (Post 667538)
you wouldn't happen to use visual studio would you? I do .NET web dev for work, but I do alot of desktop stuff in my spare time as well.

were you using an SSD before?

I'm thinking that since I rarely turn off my system anyways, a RAM drive would be nice, since VS, Office, and browsers are the only things that aren't instant on my M4. Did you ever have any data corruption/crashes related to your RAM drive?

I don't use VS, primarily PHP/MySQL/Javascript. Front end development is really nice with my livereload setup as it takes but a half second after every save to see the refreshed page, even with Compass pre-processing SASS and multiple windows refreshing, but the real time savings come when working with heavy databases.

I stated in my original post, no, I wasn't running SSD's before so I couldn't comment on the difference. All I know is my setup is lightning quick with the whole Apache/MySQL/Compass stack on the RAM drive.

If the power goes out between saves of the RAM drive image...yes you will have issues. A battery backup solves that problem though and I have never lost data or had corruption. I also work inside a dropbox folder so everything syncs externally as I work...just in case everything else fails. Hasn't been needed in the couple years I've been running the setup though.


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