How to rebalance hot files to each OST?

Environment

• AWS FSx for Lustre

Solution

1. Initially, 10 files(1GiB each) are stored on OST:0.

   [root@ip-172-31-7-64 fsx]# lfs df -h
   UUID                       bytes        Used   Available Use% Mounted on
   twxsdbmv-MDT0000_UUID      137.4G        6.4M      137.4G   0% /fsx[MDT:0]
   twxsdbmv-OST0000_UUID        1.1T       10.0G        1.1T   1% /fsx[OST:0]    <-----
   twxsdbmv-OST0001_UUID        1.1T        4.6M        1.1T   0% /fsx[OST:1]
   twxsdbmv-OST0002_UUID        1.1T        4.6M        1.1T   0% /fsx[OST:2]
   twxsdbmv-OST0003_UUID        1.1T        4.6M        1.1T   0% /fsx[OST:3]
   
   

2. Save file names to a file.

   ll | grep fio| awk '{print $NF}' > filelist
   

3. Run following script to migrate files to each OST node.

   #!/bin/bash
   ost_index=0
   while read -r line;
   do
   lfs migrate -c 1 -i ${ost_index} $line
   let ost_index+=1
   if [ $ost_index == 4 ]; then
           ost_index=0
   fi
   done < filelist
   

4. Check the result and which files are stored on OST.

   [root@ip-172-31-7-64 task1]# lfs df -h
   UUID                       bytes        Used   Available Use% Mounted on
   twxsdbmv-MDT0000_UUID      137.4G        6.4M      137.4G   0% /fsx[MDT:0]
   twxsdbmv-OST0000_UUID        1.1T        3.0G        1.1T   0% /fsx[OST:0]
   twxsdbmv-OST0001_UUID        1.1T        3.0G        1.1T   0% /fsx[OST:1]
   twxsdbmv-OST0002_UUID        1.1T        2.0G        1.1T   0% /fsx[OST:2]
   twxsdbmv-OST0003_UUID        1.1T        2.0G        1.1T   0% /fsx[OST:3]
   
   [root@ip-172-31-7-64 task1]# lfs find --ost 0 /fsx/
   /fsx//task1/fio_test_file.8.0
   /fsx//task1/rebalance.sh
   /fsx//task1/fio_test_file.0.0
   /fsx//task1/fio_test_file.4.0
   /fsx//task1/filelist