On 06.04.22 22:43, mike tancsa wrote:
On 4/6/2022 4:18 PM, Bob Friesenhahn wrote:
On Wed, 6 Apr 2022, [email protected] wrote:
WE DON'T USE COMPRESSION AS IT'S NOT SET BY DEFAULT. SOME PEOPLE
SAY YOU SHOULD HAVE IT ENABLED.... BUT.... JUST FOR AVOID HAVING
SOME DATA COMPRESSED SOME OTHER NOT (IN CASE YOU ENABLE AND LATER
DISABLE) AND FINALLY FOR AVOID ACCESSING TO INFORMATION WITH
DIFFERENT CPU COSTS OF HANDLING... WE HAVE NOT TOUCHED COMPRESSION....
There seems to be a problem with your caps-lock key.
Since it seems that you said that you are using maildir for your mail
server, it is likely very useful if you do enable even rather mild
compression (e.g. lz4) since this will reduce the write work-load and
even short files will be stored more efficiently.
FYI, a couple of our big zfs mailspools sees a 1.24x and 1.23x
compress ratio with lz4. We use Maildir format as well. They are not
RELENG_13 so not sure how zstd would fair.
I've found that Dovecot's mdbox format compresses a lot better than
Maildir (or sdbox), because it stores multiple messages per file
resulting in files large enough to contain enough exploitable reduncancy
to compress down to the next smaller blocksize. In a corporate or
education environment where users tend to send the same medium to large
attachments multiple times to multiple recipients on the same server
Dovecot's single instance storage is a game changer. It reduced my IMAP
storage requirements by a *factor* of 4.7 which allowed me to get rid of
spinning disks for the mail servers instead of playing losing games with
hybrid storage. Dovecot also supports zlib compression in the
application instead of punting it to the file system. I don't know if
Cyrus IMAP offers similar features, but if it does I would recommend
evaluating them instead of compressing or deduplicating at the file
system level.
