NS0-593 Exam Dumps : NetApp Certified Support Engineer ONTAP Specialist

• NFSv4 is a network file system protocol that supports security, performance, and scalability features. NFSv4 uses ID mapping to ensure that the permissions of files and directories are consistent across different NFSv4 servers and clients1
• ID mapping is the process of translating the user and group identifiers (UIDs and GIDs) of the local system to the user and group names (user@domain and group@domain) of the remote system, and vice versa. ID mapping is done by the idmapd service, which uses the /etc/idmapd.conf file to determine the domain name of the system2
• ID mapping requires that the NFSv4 server and client have the same domain name configured in the /etc/idmapd.conf file. If the domain names do not match, the idmapd service cannot map the UIDs and GIDs to the user and group names, and the permissions of the files and directories will be shown as nobody:nobody, which is the default anonymous user3
• Therefore, if a customer enabled NFSv4.0 on an SVM and changed the client mount from NFSv3 to NFSv4, and found that the directory owner was changed from root to nobody, the most likely cause is that the ID mapping domains do not match between the client and server. The customer should check and correct the /etc/idmapd.conf file on both systems, and restart the idmapd service and remount the NFSv4 share4

References:

1: ONTAP 9 - Network File System (NFS) - The Open Group 2: ONTAP 9 - NFSv4 and NFSv4.1 Enhancements - The Open Group 3: NFSv4 mount incorrectly shows all files with ownership as nobody:nobody - Red Hat Customer Portal 4: NFSv4 mountpoint shows incorrect ownerships as nobody:nobody in CentOS/RHEL - The Geek Diary

= A user quota is a limit on the amount of disk space or the number of files that a user can consume on a volume. A user can be represented by multiple IDs, such as UNIX user ID (UID), Windows user ID (SID), or name mapping ID. A file owned by any of these IDs is subject to the restriction of the user quota. If a user has files in different directories or qtrees within the same volume, all of those files count towards the user’s quota limit. Therefore, if other files within the volume are also owned by the user, they could exceed the user quota and prevent the user from saving more files to their home drive, even if the home drive itself shows minimal data usage. References = How quotas work with users and groups overview, ONTAP - How quotas work with users and groups

According to the SAS cabling rules and concepts for shelves with IOM12/IOM12B modules1, one of the goals is to provide a single, easily understood universal algorithm for all SAS products and configurations. One of the rules is that of the two paths to a single disk storage stack from a single node, one should connect to the top and one to the bottom of the storage stack. This ensures maximum possible resilience and minimizes the reliance on controller takeovers. The exhibit shows that both SAS connections from one controller go to the same shelf, which violates this rule and causes the error message. This situation is not normal for a FAS2750 single-node system and can reduce reliability and availability. The cables should be reconnected according to the SAS cabling rules and the controller-to-stack cabling worksheet template for quad-pathed connectivity2. References = SAS cabling rules and concepts - shelves with IOM12/IOM12B modules, SAS cabling issue: Both SAS connections from one controller go to the same shelf, Controller-to-stack cabling worksheet template for quad-pathed connectivity.