It would be interesting to compare dNFS to iSCSI-with-a-TOE-card.
Which is going to offload more burden from the database server's CPUs, I
wonder? I'm pretty sure I have never seen any analysis on this.
On Thu, May 7, 2015 at 1:07 AM, Mladen Gogala <dmarc-noreply@xxxxxxxxxxxxx>
wrote:
On 05/06/2015 03:02 PM, Kevin Jernigan wrote:
Mldaen,
The primary design goal for Direct NFS (dNFS) was / is to provide
SAN-equivalent (or better) performance, in terms of both latency and
throughput, while using NFS / Ethernet infrastructure. A secondary goal is
to simplify the configuration and tuning process for Oracle Database with
NFS storage. dNFS accomplishes these goals by implementing the NFS client
inside Oracle Database, rather then using the OS-supplied "kernel" NFS
client. This allows dNFS to skip some parts of the networking stack, and to
skip some of functionality that is required for a general-purpose NFS
client, such as write ordering. In addition, dNFS creates a separate
connection to the NFS server for each Oracle process, unlike kNFS, which
essentially multiplexes all the processes' I/O's through one or a very
small number of connections to the NFS server. There are other
optimizations in dNFS which provide major performance improvements over
kNFS, and which allow dNFS to auto-configure itself based on interrogating
the NFS server.
Well, I'll have to check it out then. I was lazy and was simply using
/etc/exports and put the nfs4 mount with the corresponding options into
/etc/fstab and that was about it. So far, I used kNFS because I know how
to configure it and have been using it for a long, long time. Usually, I
didn't have much trouble with it, if the connection was fast enough. 10GB
LAN is the norm for NFS based DB.
In general, if the NFS server can handle the workload, then dNFS can
provide SAN or iSCSI-equivalent performance, with very little configuration
work required of the DBA or system administrator.
In my experience, NFS provides better performance than iSCSI without a
specialized HBA. As I have said, I don't have numbers, just impressions.
--
Mladen Gogala
Oracle DBA
http://mgogala.freehostia.com
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