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 locks
Not 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
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).
CE