Revise the section on problems in connection with XFS

Author: jeltsch

doc/final-report/integration-notes.md

@@ -202,22 +202,22 @@ keys into a new Bloom filter and finally writing out the new Bloom filter.
 Adding such a feature would, of course, incur additional development work, but
 the infrastructure needed is present already.
 
-# Possible file system incompatibility with XFS
-
-The authors have seen at least one platform environment where there was a
-failure when using a table configuration with no disk caching (i.e.
-`DiskCacheNone`). It is unconfirmed, but the suspicion is that some versions of
-the Linux XFS file system (and at least the version on the default AWS Amazon
-Linux 2023 AMI) do not support the system call that underlies [`fileSetCaching`]
-from the `unix` package. This is an `fcntl` call, used to set the file status
-flag `O_DIRECT`. XFS certainly supports `O_DIRECT`, but it may support it only
-when the file is opened using this flag, and not when trying to set the flag on
-an already open file.
-
-A workaround is to use the EXT4 file system, or use `DiskCacheAll` for the
-table configuration (at the cost of using more memory and putting pressure on
-the page cache). If this issue is confirmed to be a widespread problem, it may
-become necessary to extend the `unix` package to allow setting the `O_DIRECT`
-flag for file open.
+# Possible incompatibility with the XFS file system
+
+We have seen at least one failure when disabling disk caching via the table
+configuration, using the `DiskCacheNone` setting. Albeit it is unconfirmed, we
+suspect that some versions of Linux’s XFS file system implementation, in
+particular the one used by the default AWS Amazon Linux 2023 AMI, do not support
+the system call that underlies [`fileSetCaching`] from the `unix` package. This
+is an `fcntl` call, used to set the file status flag `O_DIRECT`. XFS certainly
+supports `O_DIRECT`, but it may support it only when the file in question is
+opened using this flag, not when trying to set this flag for an already open
+file.
+
+This problem can be worked around by using the ext4 file system or by using
+`DiskCacheAll` in the table configuration, the latter at the cost of using more
+memory and putting pressure on the page cache. If this problem is confirmed to
+be widespread, it may become necessary to extend the `unix` package to allow
+setting the `O_DIRECT` flag upon file opening.
 
 [`fileSetCaching`]: https://hackage-content.haskell.org/package/unix-2.8.7.0/docs/System-Posix-Fcntl.html#v:fileSetCaching