Most people use the synchronous option on the NFS server. For synchronous writes, the server replies to NFS clients only when the data has been written to stable storage. Many people prefer this option because they have little chance of losing data if the NFS server goes down or network connectivity is lost.
What is sync and async in Linux?
async is the opposite of sync , which is rarely used. async is the default, you don’t need to specify that explicitly. The option sync means that all changes to the according filesystem are immediately flushed to disk; the respective write operations are being waited for.
What are 2 NFS mount options?
Common NFS mount options in Linux
- rw (read/write) / ro (read-only) – Use rw for data that users need to modify. …
- suid / nosuid. …
- hard / soft. …
- intr / nointr. …
- fg (foreground) / bg (background) …
- devs / nodevs. …
- timeo=n. …
What is NFS async?
The async option allows the NFS server to violate the NFS protocol and reply to requests before any changes made by that request have been committed to stable storage (the disk drive, for example), even if the client is set to sync.
What is Resvport?
resvport / noresvport. Specifies whether the NFS client should use a privileged source port when communicating with an NFS server for this mount point. If this option is not specified, or the resvport option is specified, the NFS client uses a privileged source port.
What does sync do on Linux?
sync command in Linux is used to synchronize cached writes to persistent storage. If one or more files are specified, sync only them, or their containing file systems.
How does sync command work?
The sync command forces an immediate write of all cached data to disk. Run sync if you anticipate the system to be unstable, or the storage device to become suddenly unavailable, and you want to ensure all data is written to disk. Individual files may be synced, or the entire filesystem containing the specified files.
How can I improve my NFS performance?
Start plenty of NFS daemon threads.
- If read dominates, add RAM on the clients to cache more of the file systems and reduce read operations.
- If write dominates, make sure the clients are using noatime,nodiratime to avoid updating access times. …
- If getattr dominates, tune the attribute caches.
What port is NFS?
NFS uses port 2049. NFSv3 and NFSv2 use the portmapper service on TCP or UDP port 111. The portmapper service is consulted to get the port numbers for services used with NFSv3 or NFSv2 protocols such as mountd, statd, and nlm.
What NFS option allows?
An NFS server can grant superuser capabilities on a shared file system on a per-host basis. To grant these privileges, use the root= hostname option to the share command. You should use this option with care.
Does NFS have cache?
NFS indexes cache contents using NFS file handle, not the file name; this means that hard-linked files share the cache correctly. Caching is supported in version 2, 3, and 4 of NFS. However, each version uses different branches for caching.
When should I use NFS?
NFS offers better performance and is unbeatable if the files are medium-sized or small. For larger files, the timings of both methods are almost the same. In the case of sequential read, the performance of NFS and SMB are almost the same when using plain text. However, with encryption, NFS is better than SMB.
What is NFS vs SMB?
NFS is used for server to server file sharing and is mostly a server-client file-sharing protocol. SMB is used for the transfer of files from the places the user needs and is mostly a user client file-sharing protocol. NFS requires AppleDouble files to share Apple extended documents.
Which is better AFP or SMB?
For a long time SMB was recommended over AFP for Mac users for stability reasons. SMB being open standard affords better implementation compared to AFP, where it has to be by necessity based on reverse engineering of the protocol.
Does macOS support NFS?
macOS natively supports NFS v3 and NFS v4, although the support for version 4 needs to be manually enabled through the /etc/nfs. conf file, since the operating system connects to version 3 by default.