Which two statements are true about the Oracle Direct Network File system (DNFS)?
A.
It utilizes the OS file system cache.
B.
A traditional NFS mount is not required when using Direct NFS.
C.
Oracle Disk Manager can manage NFS on its own, without using the operating kernel NFS
driver.
D.
Direct NFS is available only in UNIX platforms.
E.
Direct NFS can load-balance I/O traffic across multiple network adapters.
Explanation:
E: Performance is improved by load balancing across multiple network interfaces (if
available).
Note:
* To enable Direct NFS Client, you must replace the standard Oracle Disk Manager (ODM) library
with one that supports Direct NFS Client.
Incorrect:
Not A: Direct NFS Client is capable of performing concurrent
direct I/O, which bypasses any operating system level caches and eliminates any
operating system write-ordering locksNot B:
* To use Direct NFS Client, the NFS file systems must first be mounted and available
over regular NFS mounts.
* Oracle Direct NFS (dNFS) is an optimized NFS (Network File System) client that provides faster
and more scalable access to NFS storage located on NAS storage devices (accessible over
TCP/IP).
Not D: Direct NFS is provided as part of the database kernel, and is thus available on all
supported database platforms – even those that don’t support NFS natively, like Windows.
Note:
* Oracle Direct NFS (dNFS) is an optimized NFS (Network File System) client that provides faster
and more scalable access to NFS storage located on NAS storage devices (accessible over
TCP/IP). Direct NFS is built directly into the database kernel – just like ASM which is mainly used
when using DAS or SAN storage.
* Oracle Direct NFS (dNFS) is an internal I/O layer that provides faster access to large NFS files
than traditional NFS clients.
C & E.
C – Instead of using the operating system kernel NFS client, you can configure Oracl-e Database to access NFS V3 servers directly using an Oracle internal Direct NFS client.
E – Direct NFS can use up to four network paths defined for an NFS server. The Direct NFS client performs load balancing across all specified paths. If a specified path fails, then Direct NFS reissues I/Os over any remaining paths
C – TRUE
, Direct NFS Client is capable of performing concurrent direct I/O, which bypasses any operating system level caches and eliminates any operating system write-ordering locks. This decreases memory consumption by eliminating scenarios where Oracle data is cached both in the SGA and in the operating system cache and eliminates the kernel mode CPU cost of copying data from the operating system cache into the SGA.
E – TRUE
Oracle Direct NFS Client currently supports up to 4 parallel network paths to provide scalability and high availability. Direct NFS Client delivers optimized performance by automatically load balancing requests across all specified paths. If one network path fails, then Direct NFS Client will reissue commands over any remaining paths – ensuring fault tolerance and high availability.
http://www.google.pl/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0CB8QFjAA&url=http%3A%2F%2Fwww.oracle.com%2Ftechnetwork%2Farticles%2Fdirectnfsclient-11gr1-twp-129785.pdf&ei=UITkU_mwCaSS7Abdn4CYAw&usg=AFQjCNEG1C_t3zqJqpEBSjUQSjBJYZq1Ig&sig2=gPqU5aqh7hxX46nb7uXuaQ&bvm=bv.72676100,d.bGE
CE
CE
Oracle Direct NFS (dNFS) is an optimized NFS (Network File System) client that provides faster and more scalable access to NFS storage located on NAS storage devices (accessible over TCP/IP). Direct NFS is built directly into the database kernel – just like ASM which is mainly used when using DAS or SAN storage.
Direct NFS provides faster performance than what can be provided by the operating system’s NFS driver as Oracle bypasses the operating system and generates exactly the requests it needs (no user configuration or tuning required). Data is cached just once in user space, which saves memory (no second copy in kernel space). Performance is further improved by load balancing across multiple network interfaces (if available) (E).
Direct NFS Client includes two fundamental I/O optimizations to increase throughput
and overall performance. First, Direct NFS Client is capable of performing concurrent
direct I/O, which bypasses any operating system level caches and eliminates any
operating system write-ordering locks. This decreases memory consumption by
eliminating scenarios where Oracle data is cached both in the SGA and in the operating
system cache and eliminates the kernel mode CPU cost of copying data from the
operating system cache into the SGA. Second, Direct NFS Client performs
asynchronous I/O, which allows processing to continue while the I/O request is
submitted and processed.
C, E
CE
ACD;