Using a Vsuite Ramdisk for Readyboost a benefit?

Report bugs or suggestions around VSuite Ramdisk
Post Reply
jer1956
Level 2
Level 2
Posts: 8
Joined: Tue Jan 19, 2010 4:29 pm

Using a Vsuite Ramdisk for Readyboost a benefit?

Post by jer1956 »

I've noticed a number of posts about using a ramdisk for Readyboost. The purpose of Readyboost is, as the name implies, to boost readiness. That is how quick software,including the operating sysytem, loads and becomes usable. It dosn't improve performance. It is in fact a small file disk cache. Small files take longer to find on a hard drive than they do to transfer. Using Flash Memory as a cache means the time to find and transfer small files is quicker despite the lower transfer speeds. Crucially flash memory dosn't lose it's data on shutdown. So the files are available imediately during boot up, speeding it up. Using a ramdisk , which needs to load it's data during the boot process, actually slows the boot process down!
Since Readyboost is a disk cache it dosn't come fully loaded with files when you first set it up. It takes a few boots for the file system to load operating system files onto it. Equally you have to run applications a few times to get any benefit. That is why when you first enable Readyboost the cpu loading goes up. The operating system is busy working out which files will benefit from being cached on it, and loading them into the cache. Readyboost dosn't work by loading files you might need now, like Vcache. That would use up flash re-write cycles. It's more historic, storing files you have used and storing them semi-permenently so only read operations are used most of the time in the future.
The operating system already has a volatile file cache which uses ram. Taking memory to create a readyboost file cache may result in less memory for the main cache, and poorer performance. Many describe readyboost as working along side the main cache. That would be a bad design. If files are being used they should be cached in the main cache, in ram, where access is faster than flash memory. It's more sensible to see Readyboost as additional cache between the main cache and the hard drive. Large files bypass readyboost and load as fast as they can be, small files are loaded from the readyboost cache faster than form the hard drive. Either way they end up in the main ram cache. That's why it would be a waste of ram to use it for Readyboost. If you need to use a file you would end up with two copies, one in the Ram Readyboost, and another in the main Ram cache.
Last edited by jer1956 on Fri Jan 22, 2010 1:08 pm, edited 1 time in total.

User avatar
Support
Support Team
Support Team
Posts: 2750
Joined: Sun Dec 21, 2008 2:42 am

Re: Readyboost and Vsuite a benefit?

Post by Support »

Readyboost was designed to take advantage of portable flash memory storage devices. Portable flash memory devices are cheaper and available in larger size than RAM, and they have random seek times much shorter than a typical hard disk. It works like a cache of the hard disk. For eg. a computer has only 2GB ram installed, then you can dedicate a 8GB thumb drive to readyboost. It can typically cache about 16GB data of the harddisk(about 2:1 compression ratio). This shall improve the performance as compared with harddisk. Of course, you are right, the frequent write on flash memory will reduce its lifetime.

As you said, Windows also has Cache Manager running to cache data on RAM. Let's say the computer has 8GB or more RAM installed. Will Cache Manager fully utilize the available RAM to cache data? Perhaps not. This will depend on how Cache Manager was designed. It is possible that it only use 1GB RAM to cache data even if the system has 5GB RAM available.
Primo Ramdisk | PrimoCache
Romex Software Support

jer1956
Level 2
Level 2
Posts: 8
Joined: Tue Jan 19, 2010 4:29 pm

Re: Readyboost and Vsuite a benefit?

Post by jer1956 »

Perhaps my thread title was open to interpretation. I wasn't suggesting that Readyboost or Vsuite where of no benefit. I was suggesting using a Vsuite Ramdisk for Readyboost was of little benefit, especially for reducing the boot time compared to readyboost on a USB stick. I've changed the main thread title to reflect this.

Stubi
Level 5
Level 5
Posts: 47
Joined: Tue Aug 24, 2010 12:36 pm

Re: Using a Vsuite Ramdisk for Readyboost a benefit?

Post by Stubi »

jer1956 wrote: The operating system already has a volatile file cache which uses ram. Taking memory to create a readyboost file cache may result in less memory for the main cache, and poorer performance. Many describe readyboost as working along side the main cache. That would be a bad design. If files are being used they should be cached in the main cache, in ram, where access is faster than flash memory. It's more sensible to see Readyboost as additional cache between the main cache and the hard drive. Large files bypass readyboost and load as fast as they can be, small files are loaded from the readyboost cache faster than form the hard drive. Either way they end up in the main ram cache. That's why it would be a waste of ram to use it for Readyboost. If you need to use a file you would end up with two copies, one in the Ram Readyboost, and another in the main Ram cache.
You could put the ramdisk for Readyboost in the OS 32 environment into the OS Invisible Memory - and if it is just to use this memory. I have been testing this for a while with hibernation on W7 32 and so far without problems. Does Readyboost bring a performance boost? That is a different question... I start smaller and often used software like Firefox from a ramdisk anyway - this is my handmade Readyboost and hard to beat I think.

Post Reply