Sequential Reads on HD are where the hard drive seeks to a data file and starts reading and does not require the head to seek until done. This would only be the case for uploading 1 file (or more if they were lucky enough to be contiguous but that doesn't tend to happen in real life) be it 1KB or 400MB the read would be sequential.
4k Random read speed is the speed a drive can read different 4K files randomly placed on the disk. The php,html,css files etc are all around 1-4K and there are 100's of them, an update will match them against files on the server, then upload them. This scan takes the files in the order they are in the file structure which is not the order they are on the disk. This means the read is random i.e the seek head must move to a new location for each read. After the scan the upload will also be random 4k as again the files are 1-4K and not stored sequentially one after the other on disk.
But as discussed before this is all rather moot as only the fastest bleeding edge broadband nudges ahead of the 4k performance of an HD. But nice to know.
ps
Reports of the 100MB service have been around 94-98MB down and 9MB up![]()
Most people would be uploading files like photos and videos. Those are all large files, hence sequential reads. Even if you had a thousand 1KB CSS files, you would only be looking at 1MB, which is nothing. Small files don't take a lot space and that's why uploading them won't take much time, even with a hard drive. It's the growing media files which require a lot bandwidth, but luckily HDs have no effect on them.