Solved USB Flash ReadyBoost Write-Cache

[rubyrubyroo]

A dedicated ReadyBoost flash drive, running win 7 defaults to preset properties. Of concern to me is the DEFAULT policy for drive removal of a solid state flash, which is restricted to a pair of radio buttons. The first, "Quick Removal mode" IS the DEFAULT where write-cashing is DISABLED. alternatively, write cashing can be turned on using the second option "High Performance mode" although, as we all know unplugging such a drive, can quite dire consequences, often including data corruption/loss. A ".sfcashe" appears to be a single file, at least by NTFS standards, although it is unlikely accessed in the traditional manner, I still can't help but imagine a small sprinkle of corruption goes a long way, possibly rendering the entire file useless.

How, if at all, does this setting affect a ReadyBoost file, would write cashing actually be carried out on the paged virtual memory storage file? And what effects would turning of write-cashing (a.k.a. "Quick Remove mode") have on the same file entity?

In an ideal world it would be limited to a mere speed issue, but my primary concern emanates from the ultra-micro-miniaturization of such USB-flash devices, esp. where the outer grounding shell is omitted and the only anchor is a flimsy 1/16" piece of polypropylene or whatever cheap plastic they can get, which when bumped, touched, shaken or breathed on at certain angles, must bend/twist a contact or two away from the socket pin(s) on a microscopic level, leading to the two tone melody we all know as USB device disengagement, almost immidiately followed by the similar musical arrangent notifying the user that a USB device has been sensed being plugged-in.

So with win 7 will I be poised to lose my precious processes in this manner? or are the RB v-mem files outside of the "protection" of this "cashing of a cashe" (which by the way sounds terribly aquard and slow, even at flash speeds)

any advice would be appreciated
mike

 

[cluberti]

ReadyBoost data written to the cache is still backed by pages on disk, so if you pull the key during an I/O operation, the file is simply pulled from disk instead. As to corruption, ReadyBoost isn't cached, regardless of the setting, although setting any USB key to "high performance" makes it in essence no longer a removable drive. You shouldn't be doing this anyway if you're going to simply pull the device and not eject it from the taskbar before pulling this.

 

[rubyrubyroo]

i know it was a long read, but i was not going to pull the drive, i have been groing consciously aware of the miniaturization of flash drives, and most importantly their loose anchoring without an outer metal shield. They constantly will "virtually" become pulled and immediately reinserted by their weak nature, and it doesn't take more than a extremely minor touch w/ some drives, even the high end one's, as they strive to be smaller.

Also, how is a (positive) performance enhancement gained by writing to paged virtual mem, then additionally copying it to the flash IC, when before RB is activated it only has the one write to a HDD? it seems counterintuitive, at least superficially.

thanks for your previous reply, and in advance for any future assist
Mike

 

[cluberti]

No, I didn't mean the pages were duplicated, I meant they were backed - Superfetch is simply a cache for whatever is on disk, and if you pull the USB key hosting the ReadyBoost cache (which is mostly just an extension of the Superfetch cache), the request simply goes back to disk as a "miss". Nothing would ever be on a ReadyBoost key (or in the Superfetch cache itself) that wasn't already on disk.

 

[rubyrubyroo]

OHHHHH! I didn't realize that. so it basically extends the SFetch to a much faster "buffer" (the usb drive)

mike

 

[cluberti]

Well, I'd argue very few USB keys (even USB3) are faster than main system RAM, but yes - you are extending SuperFetch beyond what you have available in the system itself (a portion of RAM) to also include the USB key(s) as well, up to 8 keys (32GB a key for 256GB max ReadyBoost cache).

 

[rubyrubyroo]

ironically i was told by someone seemingly knowledgeable and of high standing in the forum that an unlimited number of usb flash drives can be used (i assume USB 2.0 - so that could potentially be 128 I joked fanned out with many powered hubs, and he knew/of no size limitations (all pertaining to win 7 as i think vista only allowed 1 flash, and made it hard to use media cards.

mike:sarc:

EDIT: I just caught your post to that other thread and got ya'

thanks for the answers
Mike

 

[cluberti]

Vista did indeed have a limit on the number of devices as 1, 4GB flash device. Also, the data on the ReadyBoost key was not persisted across power events (sleep/hibernate, reboot, etc), meaning it had to be rebuilt every time, which is not the case in Win7 (it is persistent until you remove the device from being usable via ReadyBoost). Also, the device is available to be used to precache boot data (called ReadyBoot), which a ReadyBoost key could also not do under Vista.

Also, reading/writing of a ReadyBoost cache on a flash device is a lot faster under Win7 than it was under Vista, due to improvements in the way flash devices are used, and ReadyBoost itself (also, the cache is compressed 2:1, encrypted, etc).