Let me rectify one thing: you do not need to Secure Erase a brand new SSD you just bought; those are shipped in a condition where the "HPA mapping table" is completely empty. The HPA mapping table is where the locations the Operating System has written to is being stored. With it being completely empty, that means that 100% of the visible space is used as spare area.
So what will actually do you need to do when you buy a new (Intel) SSD? Quite simple:
Step 1. Connect the SSD and setup the System BIOS to use AHCI and not "IDE emulation" as this would disable NCQ and basically lower the performance of the SSD. Modern SSDs like to be in AHCI mode. Note that AHCI is not required for TRIM; if you somehow can't use AHCI then TRIM would still work in IDE mode.
Step 2. Insert Windows 7 DVD and start setup. Once at the partition phase "Where to install Windows", click the advanced button to uncover more options and click the New button to create a new partition. When asked for the size of the new partition, create it smaller than the full capacity; leaving for example 20% unused.
Step 3. Now continue installing and nothing you need to do! Never write or format the unused space on your SSD; just never touch it.
So what will actually happen when you follow this advice?
1. You install Windows; the SSD gets to write at the beginning of the drive as Windows sees it; the SSD will see both sequential and random writes (smaller than 128KiB). The sequential writes will be written to where Windows thinks they are written. The smaller writes either write at the location where Windows thinks; or it may choose to 'remap' these to another location without knowledge of Windows. This is called write remapping, and all these 'redirections' are stored in the HPA mapping table in every modern SSD controller.
The point is, if Windows writes 4KiB to a block on the SSD which already partly contains data, then the SSD has to do a lot of work to write that 4KiB:
- read the current contents
- erase the 128KiB block
- write 128KiB containing both old (untouched) and new data
So just because where Windows wrote was close to a location where data was already stored, the SSD has to do alot more work and also alot more write cycles. So this is the reason modern SSDs like Intel remap small writes to different locations than where Windows thinks they are being stored; and remembers this in the HPA or Host Protected Area mapping table.
So both data is static and dynamic from the SSD point of view. As you've just installed Windows, you can do a simple HDTune benchmark and you would see a lower performance at the spots where you've written to (particularly, where small writes or modifications have happened, causing that location to become dynamic or remapped). This would show as the following graph:
This kind of performance degradation is not avoidable and minor in comparison. Since SSDs are so fast, a mere 10 or 20 percent slower would not be noticeable. Large files written would show the maximum speeds, but at places where small writes have happened there would be some degraded performance.
So we just accept this minor performance degradation and continue using our SSD.
2. Now we are a month later. Due to all installs/uninstalls and reinstalls and general use over time, the Operating System has at least once written to all sectors of the partition, but not to the unpartitioned area we left unused earlier when installing Windows 7.
So now, the SSD only has its internal spare (6.8%) - the space we left unpartitioned (~20%?) - plus anything we can use with TRIM.
3. Now assume the filesystem has been very full and seen a large number of random writes due to heavy usage over time, say half a year. The filesystem was frequently more than 70% full and sometimes very full (90%+). This caused a lot of fragmentation both on the filesystem level and on the SSD level.
So now there is very little "static" data but a lot of "dynamic" data. We can see degradation became a little bit stronger, but still not degraded rapidly, as it would have been if you didn't reserve that ~20% extra spare space.
This is because with the extra 20% spare space, the SSD has a huge quantity of completely empty cells that are not written to by the Operating System at all so they are 100% dedicated to the SSD. This is much more "quality space" than with TRIM, where only snippets of data are available to the SSD and only few 100% empty erase blocks which are 128KiB in size for Intel SSDs and 512K+ on others.
So if you didn't reserve the space but relied totally on TRIM, you would still see much lower random I/O performance due to shortage of empty empty blocks; there is free space available to the SSD but it is all scattered across the logical LBA (what Windows sees). Thus; lower performance and higher write amplification (= more write cycles = lower lifespan).
So you don't need to Secure Erase a brand new SSD, but you need to it if it has previously been used 'improperly' and you want to do it right and start over fresh. The Secure Erase would erase all knowledge of where the Operating System stored data; it does NOT write to the flash cells themselves. Your data is still there, but completely corrupted due to the SSD having lost all data of how it was stored with relation to how Windows thinks it is being stored. All space would be spare space again; dedicated to the SSD until at least one write happens to that location and is 'claimed' by the Operating System.
So to summarize:
1. brand new SSD? continue; used SSD? Secure Erase.
2. Set to AHCI mode
3. Boot Windows 7 setup
4. Create partition 20% smaller than full capacity.
5. Prevent filling up the drive beyond 80%.
But why do i have to sacrifice so much storage space to keep my SSD fast?
Well, this method would give you more
usable space while still preventing heavy performance degradation. You can go ahead and create a 100% sized partition and just rely on TRIM to do its work, you would need to prevent your SSD from filling up more than 50/60% to trigger erase block fragmentation. So in essence, space given to the SSD using TRIM is of less quality than space 100% dedicated (or technically said: space that is contiguous) to the SSD.
So it's either:
100% partition and 50% filesystem used capacity
80% partition and 80% filesystem used capacity
When looking at this way, you actually don't lose anything and can actually use more space on your filesystem.
Some other notes:
- Never write to filesystems more than 90% full, it triggers bad filesystem fragmentation including system files if you do an update, etc.
- Never defragment your SSD!!! This will only makes things MUCH worse! You would be doing the exact opposite: cause extreme fragmentation and 100% dynamic data on the SSD.
- Testing this theory by writing large sequential files will not help. Sequential files are written as static data without degradation; it is the smaller random writes that hurt. That also means that performing AS SSD and CrystalDiskMark benchmarks a lot will actually be quite bad if you do not have TRIM. If you do have TRIM, all those random writes would simply disappear again and given back to the SSD; phew!
So to test this theory, actual heavy use after time especially with a nearly full filesystem would surely trigger heavy erase block fragmentation and yield very poor benchmarks results (and actual performance as well).