E20-585 Specialist - Systems Administrator, Data Domain Exam Questions and Answers

If you have mounted the NFS filesystem using hard mount, it will repeatedly retry to contact the server. Once the server is back online, the program will continue to execute undisturbed from the state where it was during server crash. We can use the mount option “intr” which allows NFS requests to be interrupted if the server goes down or cannot be reached. Hence the recommended settings are hard and intr options.

Note: Soft Mount

Suppose you have mounted a NFS filesystem using “soft mount”. When a program or application requests a file from the NFS filesystem, NFS client daemons will try to retrieve the data from the NFS server. But, if it doesn’t get any response from the NFS server (due to any crash or failure of NFS server), the NFS client will report an error to the process on the client machine requesting the file access. The advantage of this mechanism is “fast responsiveness” as it doesn’t wait for the NFS server to respond. But the main disadvantage of this method is data corruption or loss of data. So this is not a recommended option to use.

References:

https://linoxide.com/nfs/difference-soft-hard-nfs-mount/

Under the heading “State” in the system show performance command output, there are several columns showing anybackground activities taking place in the filesystem during the sample period.

The states are:

References:

https://community.emc.com/docs/DOC-32514

Data Domain systems simultaneously support data access methods through VTL over Fibre Channel, remote Network Data Management Protocol (NDMP) access over Ethernet for network-attached storage(NAS), Network File System (NFS) and Common Internet File System (CIFS) protocols over Ethernet, and EMC Data Domain Boost. This deployment flexibility along with simple administration means that users can rapidly adjust to changing enterprise requirements.

References:

https://www.emc.com/corporate/glossary/virtual-tape-library.htm

Storage in most Data Domain systems is set up in a double parity RAID 6 configuration (two parity drives).

References:

Dell EMC Data Domain Operating System Version 6.1, Administration Guide, page 21