w_other”（该配置项是无值的）。详见libfuse官方文 档：https://github.com/libfuse/libfuse#security-implications # The file /etc/fuse.conf allows for the following parameters: # # user_allow_other - Using the allow_other mount file access to the filesystem owner, so that all users (including root) can access the files. allow_root This option is similar to allow_other but file access is nt$ touch file1 wanghai01@pubbeta1-nostest2:/tmp/fsmount$ ls -l total 0 -rw-r--r-- 0 wanghai01 neteaseusers 0 Jan 7 2079 file1 wanghai01@pubbeta1-nostest2:/tmp/fsmount$ echo "hello" > file1 wanghai0

request from * the kernel even after calls to unlink, rmdir or (when * overwriting an existing file) rename. Filesystems must handle * such requests properly and it is recommended to defer removal by forget * unless the file or directory is open, in which case the * kernel issues forget only after the release or releasedir * calls. * * Note that if a file system will be exported over NFS unmount the lookup count for all inodes implicitly drops * to zero. It is not guaranteed that the file system will * receive corresponding forget messages for the affected© XXX Page 5 of 15 * inodes.

Requirements for file systemopen-source storage ● Requirements ○ Cloud Native ○ Easy operation and maintenance ○ High performance ● CEPH ○ Complex and Large amount of codes ○ system maintenance are ● CopySet pre-allocation algorithm ● Raft Consistency protocol High performance ● pre-created file pool ● data strip like RAID ● Zero data copy ● RDMA Cloud NativeCluster topology The physical on a physical serverCurve metadata organization Curve maps virtual block devices to files Each file contains chunks scattered across storage nodes in the cluster Chunkservers are grouped by failure

Curve High performance Cloud native Distributed storage system https://www.opencurve.io/Agenda • What is Curve • Use Cases • CurveBS • Key Features • Comparing to Ceph • CurveFS • Comparing is an distributed storage system • Components • Curve Block Storage (CurveBS) • CurveBS: a high performance cloud native distributed block storage • Curve File System (CurveFS) • CurveFS: a a high performance cloud native file systemUse Cases • Container • Database • Data apps(middleware/bigdata/ai) • Data backupContainer • Aggregates underlying storage in the cloud (AWS EBS,

block device to a file. For example, block device /dev/sda corresponds to file /foo/bar in CurveBS 2. The address space of the block device /dev/sda maps to chunks of file in the system. For example, Each file (/foo/bar) contains chunks scattered all over the storage nodes. ChunkServer provides 4KB random read/write capability to support 4KB aligned read/write on block devices.CurveBS file structure look at the metadata for a file in CurveBS. 1. A file in CurveBS consists of chunks. The default size of chunk is 16MB. If the file directly maps to chunk, a 4TB file will consist of 256KB chunks

High performance Cloud native Distributed storage system https://www.opencurve.io/Agenda • CurveBS Architecture • CurveBS Topology • CurveBS Data Organization • MetaData Server (MDS) • ChunkServer considerations • Cloud NativeAgenda • CurveFS Architecture • CurveFS Data Organization • CurveFS file Organization • CurveFS MetaServer • CurveFS Client • CurveFS MKNode Flow • CurveFS Write to NativeCurveBS Roadmap • MultiRaft optimization • ParallelRaft for write • Reduce write magnification for file new write • Cooperate with Alibaba to support high-performance polardb for postgresql using CurveBS

Curve integrate to Cloud NativeCurve intro • Curve is an distributed storage system • High performance • Easiser operation • Cloud native • Curve is composed of two parts • Curve Block Storage performance cloud native distributed block storage • Curve File System (CurveFS) • CurveFS: a high performance cloud native file system (Based on CurveBS / S3 compatible Storage)Operator capability

FASYNC, O_TMPFILE 结论 参考文献 open接口原型 # man page open, openat, creat - open and possibly create a file #include int open(const char *pathname, int flags); int open(const char *pathname, int O_NDELAY O_NONBLOCK(O_NDELAY是在System V的早期版本引入的，后改进为O_NONBLOCK) flags中必须access mode：O_RDONLY, O_WRONLY, O_RDWR其中之一；© XXX Page 4 of 23 文件创建标志只影响打开操作, 文件状态标志影响后面的读写操作 file creation flags: O_CLOEXEC, O_CREAT O_CREAT, O_DIRECTORY, O_EXCL, O_NOCTTY, O_NOFOLLOW, O_TMPFILE, and O_TRUNC file status flags: O_APPEND, FASYNC, O_DIRECT, O_SYNC(O_DSYNC), O_LARGEFILE, O_NOATIME, O_NONBLOCK, O_PATH flags的含义 O_RDONLY:

+retrieve_reply +forget_multi +flock +fallocate© XXX Page 5 of 11 +readdirplus +copy_file_range +lseek 关键接口分析 init void (*init) (void *userdata, struct fuse_conn_info *conn); 根据 void (*write) (fuse_req_t req, fuse_ino_t ino, const char *buf, size_t size, off_t off, struct fuse_file_info *fi); 首先根据inode id 从缓存中查找到对应inode结构； 如果inode缓存中不存在对应的inode，则从mds获取inode所在copyset，metaserver 结构，缓存之； 判断inode结构中，对应请求[off, size]位置的空间是否有分配：如果未分配或只有部分分配空间，则调用空间分配器分配空间，并根据空间分配器返回结果，修改inode结构（包括file length）; inode修改需要持久化到底层并修改本地cache； 调用curve client接口，写curve卷对应[offset，len] 数据。 （这里涉及到一个问题，是否从fus

replicas of data. If one replica fails, the system can read and write data successfully on the other two replicas. When two copies fail at the same time, the system cannot determine the failure reason because the actual situation of the system. Estimation of availability and reliability in the three- replicas case Assume that the total number of disks in Curve system is N, the number of replicas is