256KB chunks when the chunk size is set to 16MB. There will be lots of pressure on KV storage, so we use two-level mapping and introduced segment. 2. Segment is also the granularity of space allocation users write data, they only need to select an appropriate CopySet and create a new chunk. Why use a CopySet to manage data? 1. Reduce metadata. If the replication group membership is saved for client provides services by libCurve. At first, external processes such as QEMU, Cinder, and NBD use it to access storage services provided by Curve. The client provids posix-like interface, such

it work as user you need user_allow_other in /etc/fuse.conf as # well. (This option allows users to use the allow_other option.) You need # allow_other if you want users other than the owner to access a neteaseusers 0 Apr 10 2081 folder fuse默认是不会检查文件访问权限的，它允许在文件系统中自由的实现访问控制策略或将其下放到底层文件访问机制(e.g. in case of network filesystems)。挂载参数‘default_permissions’用于启用内核自己的权限检查，而不是将权限检查推迟到文件系统，除了文件系统的任何权限检查之外，内核 if * FUSE_CAP_ASYNC_DIO is enabled and userspace submits a large * direct I/O request. In this case the kernel will internally * split it up into multiple smaller requests and submit them * to the

not available). Filesystem may store an arbitrary file handle (pointer, index, etc) in fi->fh, and use this in other all other file operations (read, write, flush, release, fsync). Filesystem may also opened the file with uint64_t gen; int flags; bool pos_locked; // pos is currently in use std::list pos_waiters; // waiters for pos UserPerm actor_perms; // struct fuse_file_info { /** Open flags. Available in open() and release() */ int flags; /** In case of a write operation indicates if this was caused by a delayed write from the page cache. If

performance Cloud native Distributed storage system https://www.opencurve.io/Agenda • What is Curve • Use Cases • CurveBS • Key Features • Comparing to Ceph • CurveFS • Comparing to Ceph • Current server fails • Precreated chunk file for volume space mapping • high performance framework • Use bthread (M bthread map N pthread) for scalability and performance on Multi-thread CPU • Lock free Ceph) 3 replicas with 9 nodes cluster each node has 20 x SSD, 2xE5-2660 v4 and 256GB mem FAULTS CASE CURVE I/O JITTER CEPH I/O JITTER COMMENT ONE DISK FAILURE 4s 7s ONE SERVER FAILURE 4s 7s SERVER

keyPrefix, e.leaderRev-1) if err != nil { // clean up in case of context cancel select {© XXX Page 6 of 30 case <-ctx.Done(): e.Resign(client.Ctx()) default: rverLeader(); StartObserverLeader observer := election.Observe(ctx) for { select { case resp, ok := <-observer: if !ok { fmt.Printf("Observe() channel closed permaturely\n") // observetimeoutcontext, observe timeout // get // keycontextetcd // grpcetcd case <-ticker.C: // mds t := time.Now() ctx, cancel := context.WithTimeout(context

(stop) { get and parse a record -> record switch (record->opcode) { case 1: deal 1 break case 2: deal 2 break case 3: deal 3 break } err handle } inode和dentry的内存管理结构 class InodeKey

reliability in the three- replicas case Assume that the total number of disks in Curve system is N, the number of replicas is R, and the data recovery Time in the case of failed disks is T. The Annual

丰富的第三方库（ssh, paramiko, request等） 用例设计原则  无需绑定特定环境，“随意拉起”  配置化（测试环境、测试负载定义）  控制用例时间（考虑一些折中方案）  Case独立性  Case通用性（兼顾curve、ceph等）  Tag规范(优先级、版本、运行时间)  最大化覆盖率（打乱操作顺序、随机 sleep）  精确性（checkpoint）  稳定性（避免环境因素、其他模块干扰）

I/O jitter delay ● Disk failure ● Server failure ● Server fake death ● Slow response Faults case curve i/o 抖动 Disk failure 4s Server failure 4s Server fake death 4s Slow response 1s frequentlyData

客户端分成NebdClient与 NebdServer两部分 2. NebdClient只做简单的转发 3. NebdServer实现大部分的客 户端逻辑Curve块存储 故障对I/O抖动延迟的影响 FAULTS CASE CURVE I/O 抖动Curve文件存储 1. 元数据服务 2. 高性能 3. 可扩展易运维 4. 云原生 设计目标Curve文件存储 1. 兼顾性能与容量的机器学习 场景 2