Updated README

README.md

@@ -110,7 +110,7 @@ You can also set automatic compaction at regular intervals with `yourDatabase.pe
 
 Keep in mind that compaction takes a bit of time (not too much: 130ms for 50k records on a typical development machine) and no other operation can happen when it does, so most projects actually don't need to use it.
 
-<!--Phyisical persistence works similarly to major databases: compaction forces the OS to physically flush data to disk, while appends to the data file let the OS handle this. That guarantees that a server crash can never cause complete data loss, at most one or two documents, while preserving performance.-->
+Durability works similarly to major databases: compaction forces the OS to physically flush data to disk, while appends to the data file do not (the OS is responsible for flushing the data). That guarantees that a server crash can never cause complete data loss, while preserving performance. The worst that can happen is a crash between two syncs, causing a loss of all data between the two syncs. Usually syncs are 30 seconds appart so that's at most 30 seconds of data. <a href="http://oldblog.antirez.com/post/redis-persistence-demystified.html" target="_blank">This post by Antirez on Redis persistence</a> explains this in more details, NeDB being very close to Redis AOF persistence with `appendfsync` option set to `no`.
 
 
 ### Inserting documents