Add "SSD" acronym mention for solid state drive mention.

diff --git a/doc/src/sgml/wal.sgml b/doc/src/sgml/wal.sgml
index 1cc5c6f7eb8ff6bfffb591201bd8fc5a156b4cb5..b69bc0be680fd7a984e206f5d235ee920c9b7639 100644 (file)
--- a/doc/src/sgml/wal.sgml
+++ b/doc/src/sgml/wal.sgml
@@ -1,4 +1,4 @@
-
+
 
 
  Reliability and the Write-Ahead Log
@@ -61,7 +61,7 @@
    particularly likely to have write-back caches that will not survive a
    power failure, though ATAPI-6 introduced a drive cache
    flush command (FLUSH CACHE EXT) that some file systems use, e.g. ZFS.
-   Many solid-state drives also have volatile write-back
+   Many solid-state drives (SSD) also have volatile write-back
    caches, and many do not honor cache flush commands by default.
    To check write caching on Linux use
    hdparm -I;  it is enabled if there is a * next