0

AFAIK SSD's controllers are distributing writes over free space on the disk, trying to equalize usage of memory cells. Now let's image that I have 40GB of free space on SSD, and running VirtualBox with 4GB virtual disk. Are SSD's controllers such a low-level, that they will phisycally spread the writes across 40GB anyway, or only over these 4GB used by virtual disk's binary file (and then it will shorten ssd's lifetime)?

JohnRambo
  • 11
  • 1
  • In most cases the controller would try to write equally – Ramhound Apr 21 '14 at 19:21
  • possible duplicate of [How is SSD lifetime affected by usage pattern and amount of free space?](http://superuser.com/questions/410166/how-is-ssd-lifetime-affected-by-usage-pattern-and-amount-of-free-space) – Ƭᴇcʜιᴇ007 Apr 21 '14 at 19:24
  • 1
    Modern SSDs incorporate [Wear Leveling](http://en.wikipedia.org/wiki/Wear_leveling) to distribute writes across the whole drive to prevent wearing out specific cells. – Ƭᴇcʜιᴇ007 Apr 21 '14 at 19:25
  • @technie007 I can accept your answer. I heavn't heard about wear leveling before. It looks like low-level enough to handle permanent changing the same file (which is in my case virtual disk). I think this is the same situation as with pagefile. _"These mechanisms ensure that even if an application repeatedly writes data to the same logical sector, the data is distributed evenly across the medium (logical sectors are remapped to different physical sectors)."_ - http://www.truecrypt.org/docs/wear-leveling – JohnRambo Apr 21 '14 at 22:19

1 Answers1

0

It depends on how VirtualBox is setup. If you pre-allocate the diskspace, it will be one file of 4GB and the content will change, degrading those specific sectors. If you make it grow dynamically, it will be able to utilize the disk and it doesn't play.

LPChip
  • 59,229
  • 10
  • 98
  • 140
  • 1
    SSD wear-leveling will use the whole disk for writes, regardless of the file system on it. – Ƭᴇcʜιᴇ007 Apr 21 '14 at 19:30
  • @techie007 If you have the virtual drive set as a static size/location, wouldn't that prevent the host OS from moving it around for wear leveling? If the guest OS knows it is on an SSD it might do wear leveling within the virtual drive, but I doubt it would recognize it as such. – techturtle Apr 21 '14 at 22:18
  • Yes, but it's not "moved around" by the OS. The hardware controller in the SSD moves it around (physically) and lies to the OS / RAID controller (with its "correct" location). – Arthur Kay Jun 23 '15 at 19:26