NAS104 Raid decision? Xraid vs Raid 10 etc #24296869

StephenB wrote:

RAID-10 has the same disk space result as RAID-6, but does not offer the same protection benefits. It is similar to dual raid-1, in that it protects against some combinations of 2 disk failures but not all. There's a performance review here: http://www.smallnetbuilder.com/nas/nas-reviews/32104-netgear-readynas-rn104-reviewed?showall=&start=1 RAID-1, RAID-5, RAID-10, JBOD all came in ~80 MB/sec read. RAID-1, RAID-10, JBOD all came in ~50 MB/sec write. RAID-5 was slightly slower (~40 MB/sec write). They didn't test RAID-6, and this was done on very old firmware (6.0.5). So results are probably different now. If you have the time/interest, you could try some or all of these combinations and benchmark them with NAStester (http://www.808.dk/?code-csharp-nas-performance). If you do this, I'd suggest turning off antivirus protection and snapshots. I'm sure there are folks here who'd be interested in seeing your results. In any event, I'd rather have a 9 TB volume and 40 MB/s write speeds than a 6 TB volume and 50 MB/s write speeds. So with this NAS I don't think RAID-10 is a good balance. If you want to focus on ease of recovery, then dual-RAID-1 is better than RAID-10, since you can read the data using a linux boot CD (as long as the btrfs file system is supported by boot CD) without needing RAID recovery software.

Interesting points.

So lets take a look closer. I have 4 3TB disks on NAS104.

Storage results:
Raid 5: 9TB
Raid 6: 6TB
Raid 10: 6 TB

Fault Tolerance:
Raid 5: 1 disk
Raid 6: any 2 disks
Raid 10: any 1 disk, and the right combination of 2 disks

Write Speed: (io operations/ per write):
Raid 5: 4x
Raid 6: 6x
Raid 10: 2x

Read Speed benefits:
Raid 5: 3x
Raid 6: 2x
Raid 10: 4x

But this is just the technical numbers not the situational or implementation based. The question is how the 104 implements the writes and reads. Does the performance cost really make a difference?

You point out that the 104 isn't really that fast. So does that normalize the results meaning that even though Raid 10 has great read/write speed benefits, you won't really see them?

Also, your point about the network speeds is not one I considered. The benchmark you linked to showed read speeds maxing out at 80mbs and write speeds at 50mbs, so does gigabit even matter as long you are getting 100mbs?
My previous experience with raid was based as much around the speed benefits as the fault tolerance. But those were all environments where the raid array was connected directly or using a gigabit ethernet. Let's be honest, I surely plan to use the device via my wireless network where i live with speeds closer to 100mbs. I am not sure the effect though. Maybe it marginalizes the reads, but does make any write penalties inconsequential?


If the performance benefits of raid 10 aren't really taken advantage of, or the performance hits of raid 6 aren't really felt, then that makes me lean towards raid 6 or raid 5. The extra space sure would be nice, but I really want fault protection. I have seen a raid 5 array fail and become unrecoverable when a second drive failed during recovery.

This is a tough decision. I wish I had more data. I may do some benchmarks. I wish netgear had a more complete one done.