Take the 2-minute tour ×
Server Fault is a question and answer site for professional system and network administrators. It's 100% free, no registration required.

This question has got a bunch of us talking in chat, and it had me wondering:

Most of RAID 5's ugly characteristics like UREs and long rebuilds present themselves in much larger arrays. With a RAID 5, you'll have 66% disk space available and can sustain 1 disk failure. With a RAID 1E, you'll have 50% disk space available and can also sustain 1 disk failure.

Given a three disk array, in what case would it be preferable to use a RAID 1E over a RAID 5?

share|improve this question

1 Answer 1

up vote 5 down vote accepted

If you don't have a write cache, the parity calculation for writes, especially random writes, will be higher on raid-5 than some non-parity based raid like raid-1E.

share|improve this answer
    
So, if you have a high write workload and, for some reason, are stuck with a 3-disk array to handle this workload and not enough write cache to overcome the write penalty, then RAID 1E would be a better solution? –  MDMarra Jul 20 '12 at 19:05
    
Yeah, if you have enough random writes that your cache can't completely buffer them (or if you have writethrough enabled), something without parity calculations would be a way of getting around it. Raid 1E and raid 10 don't use parity. –  Basil Jul 20 '12 at 19:38

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.