Hi all, Sorry for the longish post!
I've been looking at using rsync to mirror our mailstore (BSD/mbox format, i.e. flat files consisting of concatenated plaintext messages) to a NetApp Nearstore (basically a filer with SATA rather than FC disk) mounted over NFS. I want to do this in such a way that the NetApp automatic snapshots are kept as small as possible, so hopefully several versions of the mailstore can be stored "live" (the NetApp WAFL filesystem "stores" disk blocks as they are changed). After some experimenting, I discovered that I needed "--no-whole-file" as well as "--inplace" otherwise rsync copies the entire file by default for "local" copying, including over NFS (and so the whole previous version ends up in the snapshot). This, of course, is quite CPU-hungry, but is probably worth it! I've done some playing with "--block-size" for a 80MB mailbox and found that ~16384 uses least CPU at the cost of extra blocks copied (I'm using multiples of 4096 as that's the WAFL disk-block size, I think). However 4096 is closer to the "average" message size. I'd like to use the "--append" option instead, as mailboxes frequently have messages appended and (our) users delete/move messages comparatively rarely. However, our IMAP software (Dovecot, but UW-IMAP does this too) stores important, *changing* information (UIDVALIDITY and UIDNEXT) in a header in the *first* mail message in the mailbox, so the first block (only!) fails the checksum test. I guess this means some sort of patch to add an option to do a "nearly append except the first 'n' blocks", but I'm wondering (before I reinvent a possibly square wheel) whether anybody else has tried this? Best Wishes, Chris -- --+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+- Christopher Wakelin, [EMAIL PROTECTED] IT Services Centre, The University of Reading, Tel: +44 (0)118 378 8439 Whiteknights, Reading, RG6 2AF, UK Fax: +44 (0)118 975 3094 -- To unsubscribe or change options: https://lists.samba.org/mailman/listinfo/rsync Before posting, read: http://www.catb.org/~esr/faqs/smart-questions.html
