RAID 5 Read/Write Speed as a Function of Available Space

theredcircle · n00b Joined: 08 Oct 2004 Posts: 2

I poked around the forums for a bit, but I couldn't find a solution to this particular question.

I've got a software RAID 5 array (3x120GB disks), and it's starting to get full (it's about 55% utilized at the moment). What I'd like to know is whether I can expect to see a decrease in read/write speed as more and more junk gets stored on the array. I've got a gut feeling that things will start to get mighty slow as it gets to ~70%, but I'd like to know if anyone has a more concrete idea of when the performance will crap out.

Thanks,
Don.

Eonwe · n00b Joined: 09 Feb 2004 Posts: 23

It has nothing to do with raid5 (or any kind of raid).

It may become slower for two reasons but it's applicable to any disk.

The beginning of hard drive has usually a better transfert rate than the end.

Most filesystem have difficulty with fragmentation when more than 85% full.