[CentOS] NFS not recognizing available file space

Thu Feb 6 17:12:41 UTC 2014
James A. Peltier <jpeltier at sfu.ca>

----- Original Message -----
| Hi James,
| My system did not recognize the delaylog option,
| but when I mounted with nobarrier,inode64
| things worked and I was able to write to the
| array!
| Thanks!
| Pat

The actual reason that this worked is the inode64 option and nothing else.  Please note that this will remove backward compatibility with some older systems (very old).  I hope you understand what it is that inode64 does, if not the following URL describes it


The nobarrier option disabled write barriers and so writes are faster.  The *only* reason I enabled this is because you said you had a RAID card, which I *assumed* was battery backed.  Should your machine disks not be battery backed I would request that you remove this option as it will be more dangerous if you don't have UPS or battery backed up RAID controller.  In either case, I do also recommend that you use the deadline disk I/O scheduler which will make either option even more safe.

If you have a battery backed RAID controller deadline will have no real performance hit unless you have REALLY slow disks behind it.  XFS does some pretty extensive caching and so again, unless there are other issues you have with the equipment.  

Sorry about delaylog, that's a CentOS 6 option that is unavailable in 5.8 but if you should move to CentOS 6 it's an option that you will want to check out for additional increased performance.

There are various other tweaks that you can use to increase performance such as those surrounding file system caches.  CentOS 6 includes a tool called tuned-adm which has various predefined profiles that you can assign to a machine.  Profiles like throughput-performance, virtual-host, virtual-guest as well as enterprise-storage.  You may wish to have a look at the tunables that the profiles set and apply them manually to your CentOS 5 machine where applicable.

Glad to see this helped though! :)

James A. Peltier
Manager, IT Services - Research Computing Group
Simon Fraser University - Burnaby Campus
Phone   : 778-782-6573
Fax     : 778-782-3045
E-Mail  : jpeltier at sfu.ca
Website : http://www.sfu.ca/itservices

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