Are Delete operations written to AppendOnlyFile in Redis?
Yes. Every modification (also delete) of data gets written to AOF. See Redis persistence demystified blog posting.


  Append only file The Append Only File, usually called simply AOF, is
  the main Redis persistence option. The way it works is extremely
  simple: every time a write operation that modifies the dataset in
  memory is performed, the operation gets logged. The log is produced
  exactly in the same format used by clients to communicate with Redis,
  so the AOF can be even piped via netcat to another instance, or easily
  parsed if needed. At restart Redis re-plays all the operations to
  reconstruct the dataset.
  
  To show how the AOF works in practice I'll do a simple experiment,
  setting up a new Redis 2.6 instance with append only file enabled:

./redis-server --appendonly yes

  
  Now it's time to send a few write commands to the instance:

redis 127.0.0.1:6379&gt; set key1 Hello
OK
redis 127.0.0.1:6379&gt; append key1 " World!"
(integer) 12
redis 127.0.0.1:6379&gt; del key1
(integer) 1
redis 127.0.0.1:6379&gt; del non_existing_key
(integer) 0

  
  The first three operations actually modified the dataset, the fourth
  did not, because there was no key with the specified name. This is how
  our append only file looks like:

$ cat appendonly.aof 
*2
$6
SELECT
$1
0
*3
$3
set
$4
key1
$5
Hello
*3
$6
append
$4
key1
$7
 World!
*2
$3
del
$4
key1

  
  As you can see the final DEL is missing, because it did not produced
  any modification to the dataset.