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A filesystem library based in librados
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============================================== libradosfs - A filesystem library based in RADOS ============================================== libradosfs is a complete client-side implementation of filesystem-like functionality based on the RADOS object store (Ceph). libradosfs was designed according to the requirements of the CERN Data Storage Services group in terms of scalability and flexibility: it provides a scale-out namespace and pseudo-hierarchical storage view with optimized directory and file access (no strict POSIX semantics), parallel metadata queries, modification time propagation, file striping and other features. libradosfs should not be confused with CephFS. CephFS is a high-performance POSIX-compliant filesystem implementation built on top of RADOS and supported by Inktank/Redhat. libradosfs is published under the terms of the LGPLv3 license: http://www.gnu.org/licenses/lgpl-3.0.html Usage ====== Here is a quick example of how to use libradosfs (it might also be a good idea to take a look at the unit tests for further examples): #include <libradosfs.hh> int ret; // Initialize libradosfs radosfs::Filesystem fs; ret = fs.init("someusername", "/path/to/conf/ceph.conf"); if (ret != 0) return ret; // Add pools for prefixes fs.addDataPool("data-pool", "/"); fs.addMetadataPool("mtd-pool", "/"); // Create a directory radosfs::Dir dir(&fs, "/users"); ret = dir.create(); if (ret != 0) return ret; // Create a directory for a user with UID and GID = 1000 radosfs::Dir userdir(&fs, "/users/joe"); ret = userdir.create(S_IRWXU, , false, 1000, 1000); if (ret != 0) return ret; // Change the current UID and GID to the user mentioned above // (further operations will be done under these ids) radosFs.setIds(1000, 1000); // Create a file as user 1000 radosfs::File file(&radosFs, "/userdir/myfile"); ret = file.create(); if (ret != 0) return ret; Tools ====== libradosfs comes with a libradosfs-fsck tool for checking the filesystem for issues and possibly correct them. Here is how to use it: $ libradosfs-fsck --conf=CLUSTER_CONF /:data-pool:mtd-pool --check-dirs=/users -R Check the directory "/users" recursively in the cluster configured by CLUSTER_CONF with the data pool "data-pool" and metadata pool "mtd-pool" set for objects with the prefix "/" (all files and directories) $ libradosfs-fsck --conf=CLUSTER_CONF /:data-pool:mtd-pool --check-paths=/users/joe/file1,/trash/ Simply check the file "/users/joe/file1" and the directory "/trash/" (does not check its entries) using the cluster and pools configured as in the previous example. $ libradosfs-fsck --conf=PATH_TO_CLUSTER_CONF /:data-pool:mtd-pool --check-dirs=/ -R --fix Checks all files and directories recursively in the filesystem. When a fixable issue is found, it will be fixed. Currently, the only fixable issues are broken links (to inodes, in the logical path objects) and broken back links (in inodes, to their logical path objects). $ libradosfs-fsck --conf=PATH_TO_CLUSTER_CONF /:data-pool:mtd-pool --check-inodes --fix Checks all the inode objects in the configured pools ("data-pool" and "mtd-pool") and attempts to fix the issues found. As mentioned before, the only fixable issues are broken links in both directions. $ libradosfs-fsck --conf=PATH_TO_CLUSTER_CONF --check-inodes=data-pool-2 Checks all the inode objects in the given pool ("data-pool"). In this case, since there are no pools configured, the check will be less thorough than in the previous example. Whenever the --fix option is used, the --dry option can also be included so it only reports what would have been fixed, without really doing it. Using the --verbose option (or -v) will show all the issues found and not only a summary. If used together with the fix option, it will show what was fixed and how. If the dry run option is also used, it will show what would be done for each fix attempt.