Does disk partitioning impact performance?

Question

I will soon buy a 4 TB HDD and I am wondering if I should split it since it has so much space. My question is: will doing this affect my computer's performance? If I would keep everything in one disk, would it get slower when I use up about 3.9 TB of space?

Answer 1

Does partitioning affect performance? Absolutely! Will things get slower as the drive fills up and gets used? Yes! BUT will this performance be noticeable in real world, perceivable performance? Probably only a small amount to not noticeable at all on a drive like you mentioned given today's circumstances.

Partitioning a drive down for the OS and "short stroking" it absolutely affects synthetic performance. The first and biggest speed hindrance is the seek time of a drive. Mostly this matters when accessing and reading small files. When the drive is accessing many small files, it will spend more time looking for the files by physically moving the head to the correct location and then waiting for the data to arrive at the head, than actually transferring data. While today's modern operating systems are suppose to manage files to minimize the seek time, making a dedicated OS partition of minimal size (fully loaded with 25%-33% free space) guarantees your files you use most actively, the OS files and program files, will be located physically close together on the drive minimizing seek time.

The other performance peccadillo of platter drives is the data is transferred at different rates depending on the location the data is read from the drive. A hard drive spins at a constant RPM. This means the linear velocity, or speed at which the data moves across the head, is higher or lower depending on the location on the platter. Simply put, the data at the edge moves faster across the read head and therefore transfers faster than data in the middle or at the end. Graphing transfer rates across a drive makes this obvious. Further the first partition is at the edge and the last partition is in the middle (typically) so the first partition data will be read faster than the subsequent partitions.

The worst case scenario of past Microsoft OS's was the data was not organized. So as files got updated, they went wherever they could. This lead to small little OS and program files that began close together, but quickly got spread across the drive as updates were done and programs were removed and installed at later dates. This could mean out of 100's or 1000's of files accessed during the loading of a program and the OS, the head would be seeking much more that it would be reading. Short stroking solved this and used to be a large real world performance increase.

For real world performance these days, while short stroking does increase performance because of the physical implications of data location and drive mechanics, it does not have quite the real world effect that is used to. This is because OS's manage the locations of the files much better and they utilize RAM more to cache files so the files are not actually read from the drive as often as they used to be. There are definitely more reasons than this.

But be it as it may, if we are using a platter drive, we still partition it for the guaranteed performance increase, small as it maybe. It only takes a short time to set up, and then you just leave it. Part of our process is moving all personal and temporary files off the OS partition as well to ensure the OS drive does not outgrow the partition and minimize the the number of active files on the OS partition. Chrome's temporary files is (was?) the hardest part of that because we had to create a junction, but it really was still pretty simple. We also defragment (rarely) by access times with the hope that it will line up files in the order they were used. The logic does not hold perfectly, but it does help. There are other benefits to partitioning the drive unrelated to performance that we like too.

Answer 2

Partioining your hard drive will generate two (or more) virtual drives. This will isolate the two - all bad things like fragmentation or viruses etc. will be contained inside the partition, hence you can control them separately. Also, if you partition your system disk in 2 parts (one for the system itself, and one for, say, data backup) you will be able to make better use of your disk space.