[EMAIL PROTECTED] wrote:
I'm wondering if anyone has early experience with mix format and
incremental backups: in real world use with mix format what percent of OS
files change per day, and need to be backed up during an incremental
backup ?
With the legacy :-) mbx format, the smallest change (e.g. message marked
read, message deleted, new message added, etc.) resulted in the entire OS
file changing. Using common backup technology the entire OS file had to be
backed up during an incremental backup. A few years ago we found that over
70% of our user's OS files changed every day. This made incremental
backups not viable, as too much data changed every day.
I would expect with mix format, many messages that are stored longer term
to be in relatively static OS files that don't need backing up during an
incremental backup. (When a message is marked read or deleted, one expects
only the small mix status file to change. And new messages should only
change the most recent OS files used for message data.)
Anyone have early real world experience--what percentage of OS files
change per day with mix format ?
A related issue is the increase in the total number of files used to store
mbx versus mix format. (Depending on the backup technology used, the time
to perform backups and restores is sensitive to the number of OS files
involved.) Anyone have early real world experience with this issue ?
We have found that for daily backups, the size of the data needed for a
daily differential has decreased from 40-60% of the size of a full
backup (with mbx) to 5-8% of the size of the full backup with mix. The
additional files are not posing a problem for us as that issue is
dwarfed by the decrease in data that needs to be copied. The decrease
saves on backup time, load, bandwidth, and obviously backup space. We
do not have good data on weekly differentials yet, but expect similar
savings.
-Erik Kangas
LuxSci.com
Alex Nishri
University of Toronto
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