Given the performance level of hardware today, I don't believe parity calculation is really causing much if any slowdown for parity raid, just like encryption realistically does not caus any slowdown on modern hardware.
As for what to use, I use OpenMediaVault at home and have a RAID6 6x8TB array using native BTRFS. Yes, there's a big warning on the BTRFS wiki about parity raid, however the issue is mitigated by using non-parity raid for metadata, in which case I use raid1c3 when using raid6 for data on BTRFS. This ensures the array can survive a 2 disk failure, even if a disk fails after a poweroff.
The advantage of BTRFS over ZFS or regular mdadm raid is that you can add/remove individual drives without having to re-create the entire array, or change it to a different kind of raid should you want to. For instance, lets say you started with RAID6 then decided you wanted additional performance of RAID10 in exchange for losing some usable space, you just rebalance the array to RAID10 and it will reconfigure everything online. It may take a while, however it's still fault tolerant while it's rebalancing. You can even pause/stop the rebalancing, reboot, etc., while in progress and resume later when needed; the existing data will remain at the original raid level while any new data written will be at the new level.
If you actually read the wiki, it's apparent that the "write-hole" they're concerned about is never going to be fixed, and in fact exists in other raid implementations such as mdadm. The only reason there's a big warning and is considered a bug is because their goal is for the filesystem to be consistent all the time regardless of what happens. Given the write hole, that's impossible, however using non-parity raid for metadata works around this as the metadata will always be consistent and can then be used to repair the affected data if the parity information is incorrect.
On Fri, 2021-01-01 at 13:14 -0700, Stephen Partington via PLUG-discuss wrote:
If you are looking to just store data and use it for file access, Raid 5 should be valid. I would Use raid10 in cases where the disk activity would be database related or VM related. (Or just that much R/W IO where Raid 5 Parity calculations are killing you)
I really need a way to backup and keep track of all the media files (photos, video etc) that I've created over the years.
I've been looking at FreeNAS, OpenMediaVault and others.
Any suggestions on drives? (thinking a RAID 10 of 4 8TB drives)?
File Systems? (ext4 or ZFS or?)
Any other advice would be appreciated. (hardware, software etc)
Phil W
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