I wasn’t building RAID arrays when this paper was written, but I have always heard RAID6 is to be avoided and to just use RAID10 (or RAID5 if you don’t have enough disks). Lately I’ve heard (and agree) the conventional wisdom is to avoid hardware RAID altogether in favor of redundancy solutions at the OS level such as MDADM on Linux or Storage Spaces on Windows (macOS supports software RAID as well, created for their now-dead Fusion Drive system).
I feel like the need for a triple-redundancy option in RAID is superseded by more “advanced” software “RAID” at the file system level such as ZFS or ButterFS (to an extent). Further, the increased availability and affordability of ECC RAM in non-enterprise hardware makes the call for additional redundancy even less-urgent.
There is a nicety to having that backup battery on a RAID card for write-through operations to finish in the event of a power outage, however this is easily-solved by a UPS. In the event of a power outage, not losing any data I might have been transferring to the array is nice, but I’m still losing my OS state and any unsaved things I may have been working on.
> I feel like the need for a triple-redundancy option in RAID is superseded by more “advanced” software “RAID” at the file system level such as ZFS or ButterFS (to an extent).
ZFS has triple-parity with RAID-Z3:
> The need for RAID-Z3 arose in the early 2000s as multi-terabyte capacity drives became more common. This increase in capacity—without a corresponding increase in throughput speeds—meant that rebuilding an array due to a failed drive could "easily take weeks or months" to complete.[38] During this time, the older disks in the array will be stressed by the additional workload, which could result in data corruption or drive failure. By increasing parity, RAID-Z3 reduces the chance of data loss by simply increasing redundancy.[40]
gymbeaux|2 years ago
I feel like the need for a triple-redundancy option in RAID is superseded by more “advanced” software “RAID” at the file system level such as ZFS or ButterFS (to an extent). Further, the increased availability and affordability of ECC RAM in non-enterprise hardware makes the call for additional redundancy even less-urgent.
There is a nicety to having that backup battery on a RAID card for write-through operations to finish in the event of a power outage, however this is easily-solved by a UPS. In the event of a power outage, not losing any data I might have been transferring to the array is nice, but I’m still losing my OS state and any unsaved things I may have been working on.
throw0101b|2 years ago
ZFS has triple-parity with RAID-Z3:
> The need for RAID-Z3 arose in the early 2000s as multi-terabyte capacity drives became more common. This increase in capacity—without a corresponding increase in throughput speeds—meant that rebuilding an array due to a failed drive could "easily take weeks or months" to complete.[38] During this time, the older disks in the array will be stressed by the additional workload, which could result in data corruption or drive failure. By increasing parity, RAID-Z3 reduces the chance of data loss by simply increasing redundancy.[40]
* https://en.wikipedia.org/wiki/ZFS#ZFS's_approach:_RAID-Z_and...
The use of software versus "hardware" (firmware) does not remove the need for extra copies of data.
yieldcrv|2 years ago
NVMe SSDs, direct or over PCIe solve lots of the issue that people made RAID arrays for to begin with
sure in theory you can go even faster and redundant with RAID concepts on these nvme ssds, but tad overkill