Need to disable DART A-Time updates

Hi,

put this exact syntax on /nas/server/slot_*/param file and reboot or failover/failback the Data Mover.
Where, * is the DM number.

This is to change this parameter on an specific DM.


To change it globally, put this syntax on /nas/site/slot_param file.

Be careful when disabling this param with features like CAVA, DHSM, etc...


Gustavo Barreto.

Along the same lines, I assume would this take effect across all filesystems on that data mover? I have many CIFS VDMs - each one scanned and checked by CAVA servers - but I have one NFS filesystem I'd like to disable atime updates on. Is that possible with disabling atime updates everywhere?

Thanks!

Hi,

yes, this parameter would disable the atime updates for all filesystems on this specific DM.

What if you use the NFS client mount option "noatime" ?

from mount man page :

noatime
Do not update inode access times on this file system
(e.g, for faster access on the news spool to speed up
news servers).


Gustavo Barreto.

Great news. Turning off atime update on the datamover increased the applications read performance by 100%! Turning off atime disables all of the writes that the client has to perform every time it goes to read a file. For this NFS only application there is no concern for virus checking, backup, or any other feature where atime might be used. I destroy the data at the end of every month and start fresh so I am able to sleep at night.

It does disable it for the entire datamover so any other volume that might need atime would be impacted. It is much easier to do this on the file server than rely on your linux admin to use the option in the mount command on 60+ hosts.

Rainer,

does using noatime option with NFS mount achieve the same thing ?

I guess it's client option only ...never mind.

Message was edited by:
dynamox

no - currently its per data mover

Please open a Product Enhancement Request (PER) through Powerlink if you think a per-file system noatime option would be useful

Interesting

what Linux and kernel version do you use ?

newer Linux should have a relatime option that sounds sensible - it only updates the atime once a day

Unfortunately, noatime is not an option, thanks to some sloppy coding on service check scripts. I've used relatime on newer boxes, but we have older kernels that do not support it. I was hoping to do this just on the older filesystems, but it doesn't seem possible.

please file a PER - the more customers that are asking for it the better the chances of getting it implemented