Fast Preallocation for XFS on V10.5

Problem

If you use ALTER TABLESPACE EXTEND with big size to extend containers which using XFS on Linux, the performance might be more slow. One of possible reasons is that fast preallocation is not supported for XFS on V10.5. So we may see many times to call sqlowrite to allocate blocks ,it takes most of time. In generally, Db2 for LUW should work with all Linux filesystems, including XFS,But XFS is not one of our recommended file systems on Db2 V10.5.However some features may not be available for example fast preallocation. In the following link, chapter of Recommended file systems,we wouldn’t find XFS file system on Linux platform on V10.5 and add it into V11.1.0 in Db2 documents https://www.ibm.com/support/knowledgecenter/en/SSEPGG_10.5.0/com.ibm.db… https://www.ibm.com/support/knowledgecenter/en/SSEPGG_11.1.0/com.ibm.db… On V10.5& V11.1.0, to DB2_USE_FAST_PREALLOCATION, we also see the difference on XFS DB2_USE_FAST_PREALLOCATION on V10.5 · Operating system: AIX, Linux and Solaris on VeritasVxFS, JFS2, GPFS™, ext4 (Linux only) file systems · Default: ON for Veritas VxFS, JFS2, GPFS, and ext4, Values: ON or OFF · Allows the fast preallocation file system feature to reserve table space, and speed up the process of creating or altering large table spaces and database restore operations. This speed improvement is implemented at a small delta cost of performing actual space allocation during runtime when rows are inserted. DB2_USE_FAST_PREALLOCATION on V11.1.0 · Operating system: AIX and Linux on Veritas VxFS, JFS2, GPFS™, ext4 (Linux only) and xFS (Linux only) file systems · Default: ON for Veritas VxFS, JFS2, GPFS, ext4 and xFS, Values: ON or OFF · Allows the fast preallocation file system feature to reserve table space, and speed up the process of creating or altering large table spaces and database restore operations. This speed improvement is implemented at a small delta cost of performing actual space allocation during runtime when rows are inserted.