Hi guys
I have a little problem with a backup of MariaDB Server slave, to dump the db I am using a simple bash script

/bin/nice -n 10 ionice -c2 -n 7 /bin/mysqldump -u $username --password=$password $db | /bin/gzip > "$backupdir""$db"_"$date".gz

and it is working correctly if I start the script manually , if I set a script in crontab the zabbix allert sends me more notifications about "many processes" or "Process load is too high"
I reduce the zabbix allert using pigz and no gzip but the monitorig sends always some allert.
How can I solve this problem?

Another question, if I start the script manually the task completes in 30 minutes instead the scheduled task lasts more than 6 hours with pigz and 6 hours with the gzip.

any advice will be appreciated

Wablo

Hi Wablo,

AFAIK, piping is inherently a sequential procedure. So trying to use that with pigz which tries to process data in parallel, might not really accomplish very much. If you have the space available, I would tend to think you might want to use pigz once the entire dump file is produced.

Also, there are different compression algorithms, and depending on the details of the algorithm, there can also potentially be different ways in which a particular compression algorithm can be applied. For example, to a small amount of data, or to an entire large file at once. I wasn't certain, but I did some quick testing, and it seems that using gzip on an entire file, rather than applying it to data coming through a pipe, it tends to take less time when run on an entire file, at least in the environment I'm using.

I also have to wonder if the particular way in which you're trying to combine nice and ionice is actually accomplishing what you want. Along with that, is there any difference between the load on the database, apart from the dump procedure, at the time when you run the script manually, versus the time it is run by cron? To the extent possible, you might want to make sure that the cron job runs in a period during which there is typically the lowest load on the database engine.

Then too, depending on what you are relying, there can be differences in the context in which something is run by cron, versus the way it is run from a command line. You have to take care to make sure that any factors that the script you're running relies on in the interactive shell environment, are provided in some form, for use with a cron job.

HTH,

rigor

Hi rigor,
thanks for the reply, i am using nice and ionice to reduce the load over the server and limit the allert from zabbix, i try to split the script in 2 step as you suggested.
first step dump the DB and second step compress the dump with gizp

wablo