Questions about DFS


段世博
 

Hi~, I have two questions about DFS metadata:
   1. When the client opens a file or directory, will it check the permissions for each directory on the path, or will it only check at dfs_mount()?
   2. Will the client cache the metadata of the directory to speed up path traversal? Or the metadata of this directory will be saved on the client after the directory is opened until it is closed?
 
thanks.


Chaarawi, Mohamad
 

Hi,

 

  1. Permissions checks when using the DFS API are only done on the pool and container ACLs during dfs_mount().
  2. The DAOS/DFS client does not cache any data on the client side. So if you lookup a full path every time you are going to do the path traversal for each lookup. In DAOS master, we have added a new API (dfs_sys) where a DFS mountpoint can be done with a caching  option to cache the looked up path of parent directories to avoid such overhead:
    1. https://github.com/daos-stack/daos/blob/master/src/include/daos_fs_sys.h#L49

 

Thanks,

Mohamad

 

From: daos@daos.groups.io <daos@daos.groups.io> on behalf of 段世博 <duanshibo.d@...>
Date: Saturday, July 3, 2021 at 3:44 AM
To: daos@daos.groups.io <daos@daos.groups.io>
Subject: [daos] Questions about DFS

Hi~, I have two questions about DFS metadata:

   1. When the client opens a file or directory, will it check the permissions for each directory on the path, or will it only check at dfs_mount()?

   2. Will the client cache the metadata of the directory to speed up path traversal? Or the metadata of this directory will be saved on the client after the directory is opened until it is closed?

 

thanks.