I know the conventional wisdom is to make sure you never completely fill your SSD (always leave 10-20% free, write-leveling or something like that) but what about if you've partitioned your SSD into

  • C - 50GB
  • D - 180GB
  • E - 15GB

and after loading Win7, programs and data it looks like this

  • C - 50GB / 20GB free
  • D - 180GB / 0.5GB free
  • E - 15GB / 10GB free

Is it a problem for that D drive to be almost at capacity? There's still roughly 10%+ free overall on the drive, will the SSD be able to do it's write-leveling using the free space of the whole drive or will the space devoted to the D partition be adversely affected?

  • There have been statements (endless) on "the web" ocztechnologyforum.com/forum/… and on SSD manufactures sites own info, which lead a person to believe that "User Based overprovisioning" by manually leaving space available is effective. Even posts like this from "staff" ocztechnologyforum.com/forum/… – Psycogeek Jan 25 '12 at 7:49
  • Me&er says : By priority, the following implements would be best: 1. FW dedicated/mapped OP 2. Unformatted space not available to the OS. 3. Formatted but unused space within a separate Volume/Partition. 4. Formatted but unused space within the same Volume/Partition. . . . {This says to me "anywhere on the whole disk"} – Psycogeek Jan 25 '12 at 8:16
  • @Pyscogeek: your comments have been much more helpful than anyone else's answers or comments. If you turn them into an answer I'll gladly accept it. – LachlanG Feb 1 '12 at 3:28

The wisdom is about never completely filling a partition. It has nothing to do with anything special about SSDs or wear-leveling. In fact, it applies less to SSDs because fragmentation doesn't bother them nearly as much as it bothers rotating media.

You actually can't fill an SSD because the capacity it reports to you is less than its actual capacity. It reserves space for wear-leveling in ways that you cannot detect or affect.

  • Yes but while you can temporarily completely fill a partition on a conventional HD if you really need to with little long term implications, is the same true of an SSD? – LachlanG Jan 25 '12 at 2:54
  • I'm not sure I understand what you're asking. But if you're asking about TRIM, it depends heavily on the heuristics of the SSD and the firmware of the SSD. But that will happen regardless of whether the partition ever gets full or not, it's the total amount of data written, less the amount TRIMmed that matters. (If you half-fill a 60GB partition, then delete it, then half-fill it again, that's the same 60GB written as filling the 60GB partition.) – David Schwartz Jan 25 '12 at 2:58
  • @LachlanG: I think it's pretty clear you're trying to squash a misconception into somewhere it doesn't even apply in the first (wrong) place. – Hello71 Jan 25 '12 at 3:30
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    @Hello71: I think it's pretty clear I'm asking a simple yes/no question regardless of whether or not my question is based on a misconception. How about giving me a yes/no answer rather than snarky comment. – LachlanG Jan 25 '12 at 3:42
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    @LachlanG It's not possible to give you a simple yes or no answer because you aren't sure what it is that you are asking. The problem is the part of your question that includes the phrase "or something like that". I can tell you all about wear-leveling, but it doesn't sound like you're sure that's what you're asking about. Also, the affects of things that break TRIM, for example, don't matter if your platform doesn't support TRIM anyway. So there's no yes or no answer possible. – David Schwartz Jan 25 '12 at 4:00

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