Is it worth to buy the SAS adapter to use SAS drives for durability?

Alex Atkin UK · March 29

7 hours ago, Godlygamer23 said:

The claim that was made - intentional or not - was that hard drives are faster when full versus when empty.

Which they clarified later that they were determining this based on the flawed observation of background optimisation finishing faster. So I explained why this is flawed and actually highlights the reason why full drives are actually slower, because they can't be optimised properly when full.

Perhaps I should have clarified further, in that a drive where the files have become split across the drive (unoptimised) due to lack of free contiguous space will be slower at reads and writes, as most of the time will be spent moving the heads around than actually reading/writing the data.

kokosnh · March 29

As this topic have spin out of control I would like to clarify some points, as it's needed...

Starting from interface of HDD. SAS vs SATA.
SAS is faster, as interface, but it's not doing anything as the physical HDD is still the bottleneck.
There are 10000 and 15000 rpm drives with both SAS and SATA connector (usually SAS, but there are some SATA ones), ther's no benefit here for SAS.
SAS is redundant, as a connector, but that's that, nothing that matters for the HDD lifespan.
as for the longevity of the HDD, it doesn't matter, it's just a connector.

Next for the empty space vs faster drives.

First HDD depends on the technology:
if it's CRM, then yes, the starting sectors are faster, and it's almost linear drop in speed, as we go from first sectori to the last.
But you have to partition the HDD, not just leave empty speace, to use that. In old days, soft Short-Stroke hdd, by using partitions, was quite well known.
if it's SMR, you want to leave some empty speace, as this type of HDD, can't just rewrite the data (it's like SSD, it uses some sort of FTL, and use TRIM to clean sectors), it's need to free up some empty speace for furtre writes.
You should give it proportional free space to the amount of your writes at very least. And do give it some idle time, to do it's magic in the background.
You can't defragment this type of HDD (as it's behind sort of FTL, like SSD), and hdd is not file system awear, so with time, best thing is to just format it (secure erase), and start fresh.

second it's SSD, still depends on the technology:
If it's 3D Xpoint, then it doesn't matter
If it's NAND TLC and QLC, then you want to free up, up to 3 times more for TLC, and 4 times more for QLC of free space, to the writes for pSLC buffer to work (writes faster)
Sometimes, manufacturers leave some Over provisioning space, to mitigate that, and for wear leveling.
it's also not recommended to fill up TLC, and QLC SSD above 90-95%, as SSD writes data in paralel, to empty NAND strings, if there is no enough of empty strings to write to paraler, the write speed drops.
This also have downsides, with wear leveling algorithm, as on filled SSD, the controller can't do the magic, and realocate the data, to even out the wear on the NAND

Now for the wear leveling, and defrgmenttions.
HDD CRM, leave some speace for derfagmrntation, so it can do the magic, nothing much. The impact on life expectancy is meaningless.
HDD SMR, leave more space, as HDD needs to TRIM itself, and prepare clean space for the writes, derfagmrntation don't help, do not defragment.
SSD NAND, leave at least 90% or more, for the wear leveling algorithm to work, it do have impact on live expectancy.