Which RAID array 1+0 or 0+1 is the most reliable?

Question

RAID

Why is RAID level 1+0 one of the most fault-tolerant (better than 0+1)?

Answer 1

Because the reliability of 10 is many times higher than 01. The formulas for calculating the reliability are googled at times.

Answer 2

Both guarantee survivability in case of failure of only one of any disk. And both can withstand the absence of up to half, but strictly defined disks. Therefore, the reliability guarantees are the same - one disk of the array.
It should be mentioned that specific implementations may understand raid10 as something different from the classic examples of a mirror over a stripe or a stripe over a mirror. For example, mdadm can be configured to write raid10 in a variety of ways, including on an arbitrary number of disks (for example, raid10 on 5 disks with equal utilization of each) and with a configurable amount of redundancy (for example, to survive the death of any 2 disks, but then the total capacity of the array will be not raw/2, but raw/3)

Answer 3

These two are equal in terms of fault tolerance, if you count the extremes, but 0 + 1 is worse in terms of its recovery. If a disk fails in RAID10, then during rebuild, only one disk will be heavily loaded - its pair, and in RAID0 + 1, the load will fall on all disks at once. And when working on a configuration that has lost fault tolerance, only half of the disks are involved in RAID0 + 1, so the next crash of any disk under load will put you in a raid. In RAID10, all disks that are in service remain active, while the load on them does not change from the fact that one disk in a pair has died. Therefore, RAID0+1 is worse than RAID10.
In general, from the point of view of fault tolerance, JBOD with erasure coding N + X is better, where X can be set within fairly wide limits, but this is no longer pure RAID.

Answer 4

from the description:
for 10 - each screw is cloned to the second screw and the array above them is 0
for 01 - the array itself is cloned to the second array
, in principle, on a 2x2 array, there is not much difference, but on more capacious ones, the difference grows in favor of 10

Answer 5

Historically, the term 01 has been used for a software mirroring of two RAID0 hardware controllers, and 10 for a software stripe of two RAID1 hardware controllers.
In a fully hardware or fully software implementation, there is no difference. A stripe is written to a couple of disks, then to the next pair, and so on. and 01 out of 10 is obtained by changing the numbering of disks (which is clearly seen in the Wikipedia article, but for some reason the author of the Wikipedia article does not see this). I found several articles stating the opposite, in addition to Wikipedia, but this is as usual.