I’ve seen recommendations to use disks of the same size in a group.
Our EOS was installed 8 years ago and, as a result of successive multiple expansions, of course consists of different FST servers that have disks of different sizes from 9 to 18 TB.
Right now we’re mostly configuring directory attributes as replica:2, but we’re going to configure subdirectories in qrain.
What negative impact does a configuration with different sized drives in the same group have on EOS functionality?
If you have agroup with 8 disks and four are 9 TB and four are 18 TB, if you configure QRAIN with 8 stripes, you can only use 9TB of each disk, because for the 4 disks which still have 9TB free when the first four are full, you don’t have enough disks with free space to place 8 pieces. If you have many more disks in a group than the layout requires, this should not be a problem.
thank you very much for the prompt explanation.
I suspected that this is exactly how it works.
Since we now have 88 FST servers and there are disks of the same size on at least on 16 servers, even with qrain:12 there should be no problems.