ssd and unallocated space

[AlienTech]

Is the 'unallocated space' that is being discussed in this thread the minimum unused space on the ssd or is it something that is set by a vendor tool to define the over-provisioning capacity?

No. It is short stroking the drive so more free space is allocated by default which does not have to be erased when required. It will only help if you sequentially copy large amounts of data to the SSD which is greater than the default over provision space used by the manufacturer for garbage collection.. Unless the cpu used by the SSD is that slow, normal operations should not slow down that much as to be noticeable. Those arm cores used are pretty slow to begin with but erasing the data would take a much longer time.

 

[imagoon]

First of all, the only 100GB Enterprise SSDs that I know of, are Intel 710 series, which actually contain 160GiB of NAND.

Second, you are incorrect that TRIM was not working on my friend's drive. I ran two of them in RAID-0 (no TRIM, I was on ICH9R), and mine degraded so badly, within a week, the RAID-0 of drives was benchmarking far worse than a single drive of that type with TRIM enabled.

TRIM is only advisory. It can be used for the drive to simply "mark" what pages to reclaim when it does a GC pass. Which may only happen at idle times. My friend watches a lot of streaming video online, which streams to a temp file on the drive in the background.
Which means that it wasn't giving the drive idle time, which means that it was exhausting its "free list", and forcing a GC pass to free up blocks, which pauses drive I/O while it's waiting.

I don't agree. A streaming video gives the drive plenty of idle time. Idle time on SSD's is measured in nanoseconds. GC times are interleaved in to general use. Additionally streaming video rarely hits the disk (it is a stream after all not a download) but I digress on that point.

I am also very aware TRIM is advisory. Many of the newer drives practically ignore it once the free block count is over a certain percentage. It is also a fairly common misconception that drives clear blocks only during some sort of "garbage collection pass" inferring that it only happens "once in awhile." Garbage block clearing can and does occur during any idle pass, generally based on free space pressure.

Your description still sounds like a defective drive, bad firmware or bad BIOS or some other issue, not a reason "short stroke" an SSD. If anything it was masking the real defect. That 60GB [in disk "decimal"] drive also has 64GB of NAND [binary] which means out of the box it was sitting on a little over 8GB [binary] of protected area. I am not quite sure what your point is.