Which is faster: write two big files to separate hard drives, or write them to the same set of drives in Raid0

Question

This is sort of related to the answer here: https://superuser.com/a/325771/396863

Let's say I have a two 1 gb files which I want to simultaneously write to my hard disks. As noted in the linked answer, I could write them to separate hard disks, or use my two hard disks in Raid0 and write the two files to this raid array. Which would be faster?

Based on the comments I am providing some more details of my situation:

1. The data is being dumped from memory.
2. Not sure what hardware details I need to provide, but it is a 4 core XEON E3-1271 processor with 32 gbs of ram.

Answer 1

Assuming 2 identical drives, there may be no difference, but most likely the 2 separate hard drive scenario would be faster.

If you think about it, this must be the case - in the case of RAID0 its possible/probable that data from both files will be written to the same disk - and assuming the disk is the bottleneck - which is a reasonable assumption - you are squeezing twice as much through the bottleneck. This bottleneck does not exist with 2 disks.

Similarly, when you write a file, you ideally want to write it so everything lines up sequentially on the disk - this will increase the read speed later on. By writing the files on RAID0 you are increasing the risk of striping the data and slowing reads - thats why defragmenting a drive can speed it up. (This is not really an issue with SSD, but you specified hard disks).

Of-course, by using RAID0 you get more useable space