I had an enquiry about appropriate number of MDS & MDT volumes for a
filesystem that could potentially hold 4bn files. I expect the typical
"working size" will be much less than 1bn files.
My understanding for ldiskfs MDT volume has a ratio of 1 inode per 4096
bytes. So ldiskfs MDT volume with 1bn inodes would need a 4TB MDT size.
Using DNE, we could have 4 MDS servers, each with a 4TB MDT volume to
achieve a filesystem with 4bn inodes.
FYI, 4TB volume is a reasonable size when using SSD physical drives (ie.
16TB is not). Any recommendations for reasonable mix of number of DNE
MDS + MDT volume size to achieve 4bn files?