topology structure of CURVE. CurveBS uses the central node Metadata Server (MDS) to manage virtual disk mapping and data replicas distribution. Decentralization currently leads to excessive complexity rollback from snapshot CurveBS data organization Data organization of virtual block device in CurveBS1. CurveBS maps the virtual block device to a file. For example, block device /dev/sda corresponds support 4KB aligned read/write on block devices.CurveBS file structure of virtual block device As mentioned above, CurveBS maps virtual block devices to files. Let's look at the metadata for a file in CurveBS

data copy ● RDMA Cloud NativeCluster topology The physical pool is used to physically isolate machine resources Zone is the basic unit of fault isolation Server Indicates a physical server Chunkserver Chunkserver is a service instance 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

0; }; using Extents = std::vector; class Allocator { public: Allocator(...) {} virtual ~Allocator() = default;© XXX Page 10 of 11 /** * @brief * * @param size uint64_t */ virtual uint64_t Allocate(uint32_t size, const AllocateHint& allocateHint, Extents* extents) = 0; /** * @brief */ virtual void Deallocate(const Extents& extents) = 0; /** * @brief */ virtual bool MarkUsed(const Extents& extents) = 0; /** * @brief */ virtual bool MarkUsable(const Extents& extents) = 0; /**

S3Client() {} virtual ~S3Client() {} virtual void Init(curve::common::S3AdapterOption option) = 0; virtual int Upload(std::string name, const char* buf, uint64_t length) = 0; virtual int Append(std::string Append(std::string name, const char* buf, uint64_t length) = 0; virtual int Download(std::string name, char* buf, uint64_t offset, uint64_t length) = 0; }; metaserver.proto enum FileType { TYPE_DIRECTORY

class DiskCacheManagerImpl : public DiskCacheManager{ public: DiskCacheManagerImpl(); virtual ~DiskCacheManagerImpl() { TrimStop(); } int Init(const std::string cacheDir); maxCachedObj; // ? bthread::Mutex mtx_; }; class DiskCacheWrite { public: DiskCacheWrite() {} virtual ~DiskCacheWrite() { AsyncUploadStop(); } int WriteDiskFile(std::string fullWriteDir std::string CacheDir_; }; class DiskCacheRead { public:© XXX Page 7 of 9 DiskCacheRead() {} virtual ~DiskCacheRead() {} int ReadDiskFile(std::string name, char* buf, uint64_t offset, uint64_t

chunkPos_(chunkPos), len_(len) { data_ = new char[len]; memcpy(data_, data, len); } virtual ~DataCache() { delete data_; data_ = NULL; } void Write(uint32_t cachePos