What's faster: Moving file drives scenarios

[liqstr]

Say you're backing up some files and have two hard drives (assume both equal NTFS drives).

Is it faster to copy from drive A -> drive B,
or to copy from partition 1 on drive A -> partition 2 on drive A?

One hand, partition to partition is on the same drive, so its on the same drive, but the heads gotta move all around back and forth.
But then with two hard drives, well you have 2 drives. That's twice as many as 1. (2*1=2) So possibly twice as fast.

Thoughts? Comments? Questions? Suggestions?

 

[Valantar]

You're mixing up your terms. Do you mean moving or copying? Moving files on the same partition is nearly instantaneous, as all that needs to change is the "address" of the file. Nothing is actually moved.

For copying, it's faster between different drives, simply because putting more work on a single drive will always reduce its total performance per workload due to the added stress to the controller and speed restrictions of the interface. Even if it's an SSD with max reads of 550MB/s and writes of 500MB/s, you'll never see those numbers simultaneously. At best (and that's only with the very best drives) you'll see a total combined throughput close to the max throughput number. As an example, look at the mixed workload graphs in this review.

For moving between partitions on the same drive, this works the same as copying within the same drive (at least for HDDs that allocate specific portions of the platter per partition. For SSDs, I'm not quite sure).

 

[liqstr]

Good info. I disagree with the last part though. Try it out yourself: make a new windows partition on your drive and move a big folder across partitions.
It took a long time.

 

[VirtualLarry]

Moving files on the same partition is nearly instantaneous

move a big folder across partitions.
It took a long time.

He's not talking about the same thing. "Across partitions", means that it actually has to physically copy the data between locations. Moving files in the SAME partition just requires updating some directory entries.

 

[PliotronX]

Moving is going to be instantaneous on the same disk as the contents don't change, only the path. Copying is a different story though

Oh, I saw VLs post and reread, yeah moving between partitions will rewrite data to the destination partition and be much slower than to a different disk.

 

[Valantar]

Good info. I disagree with the last part though. Try it out yourself: make a new windows partition on your drive and move a big folder across partitions.
It took a long time.

Uhm, that's exactly what I said.

For moving between partitions on the same drive, this works the same as copying within the same drive (at least for HDDs that allocate specific portions of the platter per partition. For SSDs, I'm not quite sure).

In other words: just as copying a file (i.e. duplicating it) on the same partition will be slow (due to simultaneous sustained read and write operations to the same drive), so will moving a file across partitions on the same drive (due to exactly the same workload happening, only to a slightly different target).

 

[liqstr]

Oh sorry you're right.
>For moving between partitions on the same drive, this works the same as copying within the same drive

Off-topic Question:
Is it true an SSD can only be filled 50% before it loses performance?

 

[Elixer]

Off-topic Question:
Is it true an SSD can only be filled 50% before it loses performance?

No, not 50%.