What happens if you put another disk in RAID 5 to replace the deceased one?

Question

Hard disks

The question is, I have a raid 5 of 2.4 terabyte sas disks, with a rotation speed of 10 thousand rpm. One of the screws died, the question arose to change it to a similar and expensive one, or to one similar to 2 terabytes and 7200 rpm.
Tell me, what consequences will I get if I put a disk less fast and smaller?

Answer 1

Nothing will work - the disk must be equal or larger, but certainly not smaller.
And if you use a slower disk, the overall speed of the array will drop, and much more.

Answer 2

well, at least he will not be able to enter the raid, or he will need to be destroyed and recreated, taking into account 2tb of space on each disk,
it is logical not to be stupid and insert a 3tb disk

Answer 3

Tell me, what consequences will I get if I put a disk less fast and smaller?

None :) The controller will refuse to accept such a disk, that's all. The disc must be equal or larger in volume. As for speed, RAID5 is already not a star in terms of speed, and the appearance of one slow disk among ten-thousanders will lead to the fact that the entire array will start working as if all disks were seven-thousanders :) Well, that is, a decrease in speed by a third.

Answer 4

I think that if your hardware supported the operation of different disks in an array, then you would know about it. So buy a similar disk.
Also, I can't help but add that if you're asking this question, you might be standing close to the edge of a cliff. To be more precise, the scenario begins to resemble one of the typical ones with which they turn to us for data recovery.
Make sure you know exactly how to initiate the correct rebuild for your array. I call correct the opposite of what is called forced rebuild by a number of manufacturers. If you do the latter, then the controller will recalculate the parity for you as if the new disk contains real user data.
After that, the only chance to recover the information will be to create an image of the disk that has flown. And, of course, there will be desynchronization for those files that have changed after that.
And here a problem may arise due to the fact that "raid 5 of sas disks with a rotation speed of 10 thousand rpm" . Such disks are more reliable, less prone to failures, i.e. plow like work horses. But: for those that do fail, the probability that the disk has died irretrievably is much higher. Those. SAS-disks, if they die, die "completely" much more often.
Of course, you can have a "hysterical" controller that ejects disks at the slightest suspicion of problems, but I would not rely on it.
So take a suitable disk, and if in doubt, then before installing it, number the remaining disks of the array, connect directly, and make an uncompressed full sector-by-sector copy of each disk. Yes, it will take time and space, but with clones, even if something goes wrong, you can get everything back.
Otherwise, you risk becoming our client. You can evaluate the feasibility of the recommendations above by reading the prices for RAID recovery: https://rlab.ru/raidrecovery/