I don't recommend using RAID-5 for any sort of write-intensive work at all. RAID-5 performance is notoriously slow...
for writes, especially small writes, because of the CPU overhead that each write requires. The overhead is worse if the RAID-5 is software-based. Hardware-based RAID-5 is better, but still not as fast as RAID-1. Of course, RAID-1 requires a great deal of extra disk space (double the usable space you need), so you pay for each approach in different ways.
Can you put the OS on RAID-5? Yes, you can, but I believe you'll find that the system's performance will suffer.
Can you divide a RAIDed slice into multiple partitions? You may be able to, depending on the hardware and software you use, but I think you'd be better served by having two or more separate RAID slices, and assigning each to a separate file system.
Does RAID-5 take a long time to rebuild? Short answer: YES. Long answer: It depends on how large the RAID-5 slice is, how many disks it is striped across, the I/O speed of the disks involved, the CPU speed of the system(s) involved, how much other work is underway and lots of other factors. I have seen large, poorly configured RAID-5 slices take days to rebuild.
The optimal configuration for RAID-5 is to have data spread across four to six disks. Fewer than that is not worth it: You may as well consider RAID-1. More than that invites trouble by increasing the likelihood of multiple disk failures. And, more disks require more time to rebuild.
Dig Deeper on Disk-based backup
Related Q&A from Evan Marcus
Storage expert Evan Marcus compares software and hardware RAID and outlines the benefits and drawbacks of each. Continue Reading
This expert answer explains the purpose of creating LUNs and details reasons for creating multiple LUNs. Continue Reading
This advice details the hardware and software requirements for setting up two data servers in fail-safe cluster mode for high availability. Continue Reading
Have a question for an expert?
Please add a title for your question
Get answers from a TechTarget expert on whatever's puzzling you.