Over Provisioning

[pcslookout]

What does it exactly do and is it important for a SSD or not worth doing ?

 

[UsandThem]

If you are talking about over-provisioning, this is an article all about everything you want to know about it:

http://www.seagate.com/tech-insights/ssd-over-provisioning-benefits-master-ti/

And it is definitely worth doing.

 

[VirtualLarry]

And it is definitely worth doing.

Highly debatable.

There's already a certain percentage of factory / firmware OP. Any additional user OP over and above that may not be necessary, and may just be a waste of (expensive) SSD space.

It can also depend on your workloads, whether they are write-heavy, and / or latency-sensitive.

Edit: And modern drives with SLC caches make OP even more unnecessary, because they can coalesce writes to the SLC cache into nice even blocks to write to the rest of the NAND, so you don't need to leave huge pools of NAND free for random writes.

 

[BlueWeasel]

Assume an SSD is used as a boot/OS drive and it never goes below 50% free space.

Is OP really necessary in that scenario?

 

[UsandThem]

Highly debatable.

There's already a certain percentage of factory / firmware OP. Any additional user OP over and above that may not be necessary, and may just be a waste of (expensive) SSD space.

It can also depend on your workloads, whether they are write-heavy, and / or latency-sensitive.

The OP, in one of his many posts on SSDs, downloads about 300 GB day of stuff from news feeds. He was advised by many to use a HDD for that, which I believe he added in addition to the SSD. So, based on his usage trends, setting an OP would be advisable for his enthusiast usage.

Assume an SSD is used as a boot/OS drive and it never goes below 50% free space.

Is OP really necessary in that scenario?

I believe so. He bought a Samsung 850 Pro, and the Anandtech test of that drive showed that it comes with a 7% OP, and when it is extended to 12%:

Wow, this is awesome. Even with the default 7% over-provisioning, the 850 Pro is pushing almost as many IOPS as the Extreme Pro with its 12% over-provisioning. When the over-provisioning is increased to the same 12% level, the 850 Pro is a leader without a doubt. Only the Vector 150 can come close, although it is nowhere hear as constant as the IOPS is ranging between 10K and 30K, whereas the 850 Pro can maintain a steady line.

When compared with the 840 Pro, the upgrade is tremendous. IO consistency was always the weak point of the 840 Pro, so it is great to see that Samsung has paid a great effort to fix that in the 850 Pro. A part of the performance increase obviously comes from the usage of V-NAND because with shorter program and erase latencies, the steady-state performance increases as the garbage collection takes less time and there are more empty blocks available.

http://www.anandtech.com/show/8216/samsung-ssd-850-pro-128gb-256gb-1tb-review-enter-the-3d-era/7