Using a file name pattern of the form:

roll.log.%d

{yyyy-MM-dd'T'HH:mm:ss}

.gz

results in a regular expression of:

roll.log.
d

{4}

-
d

{2}-
d{2}

'T'
d

{2}:
d{2}

:
d

{2}

.gz

which has the unfortunate property that it does not match the actual file names which get generated:

roll.log.2011-07-11T16:42:28.gz