Unified Distributed Storage System Ceph Provides Object, Block and File Storage
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Ceph is a unified distributed storage system that provides object storage, block storage, and file storage functionality. It uses a distributed object store called RADOS that is comprised of self-managing storage nodes. Ceph uses a CRUSH algorithm to determine data placement across nodes and ensures data is replicated according to a replication policy. It uses a monitor to maintain cluster state and provide consensus across nodes.
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Unified Distributed Storage System Ceph Provides Object, Block and File Storage
- 1. ceph – a unified distributed storage system sage weil cloudopen – august 29, 2012
- 2. outline ● why you should care ● what is it, what it does ● how it works ● architecture ● how you can use it ● librados ● radosgw ● RBD ● file system ● who we are, why we do this
- 3. why should you care about another storage system?
- 4. requirements ● diverse storage needs ● object storage ● block devices (for VMs) with snapshots, cloning ● shared file system with POSIX, coherent caches ● structured data... files, block devices, or objects? ● scale ● terabytes, petabytes, exabytes ● heterogeneous hardware ● reliability and fault tolerance
- 5. time ● ease of administration ● no manual data migration, load balancing ● painless scaling ● expansion and contraction ● seamless migration
- 6. cost ● linear function of size or performance ● incremental expansion ● no fork-lift upgrades ● no vendor lock-in ● choice of hardware ● choice of software ● open
- 8. unified storage system ● objects ● native ● RESTful ● block ● thin provisioning, snapshots, cloning ● file ● strong consistency, snapshots
- 9. APP APP APP APP HOST/VM HOST/VM CLIENT CLIENT RADOSGW RADOSGW RBD RBD CEPH FS CEPH FS LIBRADOS LIBRADOS A bucket-based A bucket-based A reliable and fully- A reliable and fully- A POSIX-compliant A POSIX-compliant A library allowing A library allowing REST gateway, REST gateway, distributed block distributed block distributed file distributed file apps to directly apps to directly compatible with S3 compatible with S3 device, with aaLinux device, with Linux system, with aa system, with access RADOS, access RADOS, and Swift and Swift kernel client and aa kernel client and Linux kernel client Linux kernel client with support for with support for QEMU/KVM driver QEMU/KVM driver and support for and support for C, C++, Java, C, C++, Java, FUSE FUSE Python, Ruby, Python, Ruby, and PHP and PHP RADOS RADOS A reliable, autonomous, distributed object store comprised of self-healing, self-managing, A reliable, autonomous, distributed object store comprised of self-healing, self-managing, intelligent storage nodes intelligent storage nodes
- 10. open source ● LGPLv2 ● copyleft ● ok to link to proprietary code ● no copyright assignment ● no dual licensing ● no “enterprise-only” feature set ● active community ● commercial support
- 11. distributed storage system ● data center scale ● 10s to 10,000s of machines ● terabytes to exabytes ● fault tolerant ● no single point of failure ● commodity hardware ● self-managing, self-healing
- 12. ceph object model ● pools ● 1s to 100s ● independent namespaces or object collections ● replication level, placement policy ● objects ● bazillions ● blob of data (bytes to gigabytes) ● attributes (e.g., “version=12”; bytes to kilobytes) ● key/value bundle (bytes to gigabytes)
- 13. why start with objects? ● more useful than (disk) blocks ● names in a single flat namespace ● variable size ● simple API with rich semantics ● more scalable than files ● no hard-to-distribute hierarchy ● update semantics do not span objects ● workload is trivially parallel
- 14. DISK DISK DISK DISK DISK DISK HUMAN HUMAN COMPUTER COMPUTER DISK DISK DISK DISK DISK DISK DISK DISK
- 15. DISK DISK DISK DISK HUMAN HUMAN DISK DISK HUMAN HUMAN COMPUTER COMPUTER DISK DISK DISK DISK HUMAN HUMAN DISK DISK DISK DISK
- 16. HUMAN HUMAN HUMAN HUMAN HUMAN HUMAN HUMAN HUMAN DISK DISK HUMAN HUMAN HUMAN HUMAN DISK DISK HUMAN HUMAN HUMAN HUMAN DISK DISK DISK DISK HUMAN HUMAN DISK DISK HUMAN HUMAN HUMAN HUMAN DISK DISK (COMPUTER)) (COMPUTER HUMAN HUMAN DISK DISK HUMAN HUMAN HUMAN HUMAN DISK DISK HUMAN HUMAN HUMAN HUMAN DISK DISK HUMAN HUMAN DISK DISK HUMAN HUMAN DISK DISK HUMAN HUMAN HUMAN HUMAN DISK DISK HUMAN HUMAN HUMAN HUMAN (actually more like this…)
- 17. COMPUTER COMPUTER DISK DISK COMPUTER COMPUTER DISK DISK COMPUTER COMPUTER DISK DISK HUMAN HUMAN COMPUTER COMPUTER DISK DISK COMPUTER COMPUTER DISK DISK COMPUTER COMPUTER DISK DISK HUMAN HUMAN COMPUTER COMPUTER DISK DISK COMPUTER COMPUTER DISK DISK COMPUTER COMPUTER DISK DISK HUMAN HUMAN COMPUTER COMPUTER DISK DISK COMPUTER COMPUTER DISK DISK COMPUTER COMPUTER DISK DISK
- 18. OSD OSD OSD OSD OSD FS FS FS FS FS btrfs xfs ext4 DISK DISK DISK DISK DISK M M M
- 19. Monitors: • Maintain cluster membership and state M • Provide consensus for distributed decision-making • Small, odd number • These do not serve stored objects to clients Object Storage Daemons (OSDs): • At least three in a cluster • One per disk or RAID group • Serve stored objects to clients • Intelligently peer to perform replication tasks
- 20. HUMAN M M M
- 21. data distribution ● all objects are replicated N times ● objects are automatically placed, balanced, migrated in a dynamic cluster ● must consider physical infrastructure ● ceph-osds on hosts in racks in rows in data centers ● three approaches ● pick a spot; remember where you put it ● pick a spot; write down where you put it ● calculate where to put it, where to find it
- 22. CRUSH • Pseudo-random placement algorithm • Fast calculation, no lookup • Repeatable, deterministic • Ensures even distribution • Stable mapping • Limited data migration • Rule-based configuration • specifiable replication • infrastructure topology aware • allows weighting
- 23. 10 10 01 01 10 10 01 11 01 10 10 10 01 01 10 10 01 11 01 10 hash(object name) % num pg 10 10 10 10 01 01 01 01 10 10 10 10 01 01 11 11 01 01 10 10 CRUSH(pg, cluster state, policy)
- 24. 10 10 01 01 10 10 01 11 01 10 10 10 01 01 10 10 01 11 01 10 10 10 10 10 01 01 01 01 10 10 10 10 01 01 11 11 01 01 10 10
- 25. RADOS ● monitors publish osd map that describes cluster state ● ceph-osd node status (up/down, weight, IP) M ● CRUSH function specifying desired data distribution ● object storage daemons (OSDs) ● safely replicate and store object ● migrate data as the cluster changes over time ● coordinate based on shared view of reality ● decentralized, distributed approach allows ● massive scales (10,000s of servers or more) ● the illusion of a single copy with consistent behavior
- 26. CLIENT CLIENT ??
- 29. CLIENT ??
- 30. APP APP APP APP HOST/VM HOST/VM CLIENT CLIENT RADOSGW RADOSGW RBD RBD CEPH FS CEPH FS LIBRADOS A bucket-based A bucket-based A reliable and fully- A reliable and fully- A POSIX-compliant A POSIX-compliant A library allowing REST gateway, REST gateway, distributed block distributed block distributed file distributed file apps to directly compatible with S3 compatible with S3 device, with aaLinux device, with Linux system, with aa system, with access RADOS, and Swift and Swift kernel client and aa kernel client and Linux kernel client Linux kernel client with support for QEMU/KVM driver QEMU/KVM driver and support for and support for C, C++, Java, FUSE FUSE Python, Ruby, and PHP RADOS RADOS A reliable, autonomous, distributed object store comprised of self-healing, self-managing, A reliable, autonomous, distributed object store comprised of self-healing, self-managing, intelligent storage nodes intelligent storage nodes
- 31. APP APP LIBRADOS LIBRADOS native M M M M M M
- 32. LIBRADOS L • Provides direct access to RADOS for applications • C, C++, Python, PHP, Java • No HTTP overhead
- 33. APP APP APP APP HOST/VM HOST/VM CLIENT CLIENT RADOSGW RBD RBD CEPH FS CEPH FS LIBRADOS LIBRADOS A bucket-based A reliable and fully- A reliable and fully- A POSIX-compliant A POSIX-compliant A library allowing A library allowing REST gateway, distributed block distributed block distributed file distributed file apps to directly apps to directly compatible with S3 device, with aaLinux device, with Linux system, with aa system, with access RADOS, access RADOS, and Swift kernel client and aa kernel client and Linux kernel client Linux kernel client with support for with support for QEMU/KVM driver QEMU/KVM driver and support for and support for C, C++, Java, C, C++, Java, FUSE FUSE Python, Ruby, Python, Ruby, and PHP and PHP RADOS RADOS A reliable, autonomous, distributed object store comprised of self-healing, self-managing, A reliable, autonomous, distributed object store comprised of self-healing, self-managing, intelligent storage nodes intelligent storage nodes
- 34. APP APP APP APP REST RADOSGW RADOSGW RADOSGW RADOSGW LIBRADOS LIBRADOS LIBRADOS LIBRADOS native M M M M M M
- 35. RADOS Gateway: • REST-based interface to RADOS • Supports buckets, accounting • Compatible with S3 and Swift applications
- 36. APP APP APP APP HOST/VM HOST/VM CLIENT CLIENT RADOSGW RADOSGW RBD CEPH FS CEPH FS LIBRADOS LIBRADOS A bucket-based A bucket-based A reliable and fully- A POSIX-compliant A POSIX-compliant A library allowing A library allowing REST gateway, REST gateway, distributed block distributed file distributed file apps to directly apps to directly compatible with S3 compatible with S3 device, with a Linux system, with aa system, with access RADOS, access RADOS, and Swift and Swift kernel client and a Linux kernel client Linux kernel client with support for with support for QEMU/KVM driver and support for and support for C, C++, Java, C, C++, Java, FUSE FUSE Python, Ruby, Python, Ruby, and PHP and PHP RADOS RADOS A reliable, autonomous, distributed object store comprised of self-healing, self-managing, A reliable, autonomous, distributed object store comprised of self-healing, self-managing, intelligent storage nodes intelligent storage nodes
- 37. COMPUTER COMPUTER DISK DISK COMPUTER COMPUTER DISK DISK COMPUTER COMPUTER DISK DISK COMPUTER COMPUTER DISK DISK COMPUTER COMPUTER DISK DISK COMPUTER COMPUTER DISK DISK COMPUTER COMPUTER COMPUTER COMPUTER DISK DISK DISK DISK COMPUTER COMPUTER DISK DISK COMPUTER COMPUTER DISK DISK COMPUTER COMPUTER DISK DISK COMPUTER COMPUTER DISK DISK COMPUTER COMPUTER DISK DISK
- 38. COMPUTER COMPUTER DISK DISK COMPUTER COMPUTER DISK DISK COMPUTER COMPUTER DISK DISK COMPUTER COMPUTER DISK DISK VM VM COMPUTER COMPUTER DISK DISK COMPUTER COMPUTER DISK DISK VM VM COMPUTER DISK COMPUTER DISK COMPUTER COMPUTER DISK DISK VM VM COMPUTER COMPUTER DISK DISK COMPUTER COMPUTER DISK DISK COMPUTER COMPUTER DISK DISK COMPUTER COMPUTER DISK DISK
- 39. VM VM VIRTUALIZATION CONTAINER VIRTUALIZATION CONTAINER LIBRBD LIBRBD LIBRADOS LIBRADOS M M M M M M
- 40. CONTAINER CONTAINER VM VM CONTAINER CONTAINER LIBRBD LIBRBD LIBRBD LIBRBD LIBRADOS LIBRADOS LIBRADOS LIBRADOS M M M M M M
- 41. HOST HOST KRBD (KERNEL MODULE) KRBD (KERNEL MODULE) LIBRADOS LIBRADOS M M M M M M
- 42. RADOS Block Device: • Storage of virtual disks in RADOS • Decouples VMs and containers • Live migration! • Images are striped across the cluster • Snapshots! • Support in • Qemu/KVM • OpenStack, CloudStack • Mainline Linux kernel
- 43. HOW DO YOU SPIN UP THOUSANDS OF VMs INSTANTLY AND EFFICIENTLY?
- 44. instant copy 144 0 0 0 0 = 144
- 45. write CLIENT write write write 144 4 = 148
- 46. read read CLIENT read 144 4 = 148
- 47. APP APP APP APP HOST/VM HOST/VM CLIENT CLIENT RADOSGW RADOSGW RBD RBD CEPH FS LIBRADOS LIBRADOS A bucket-based A bucket-based A reliable and fully- A reliable and fully- A POSIX-compliant A library allowing A library allowing REST gateway, REST gateway, distributed block distributed block distributed file apps to directly apps to directly compatible with S3 compatible with S3 device, with aaLinux device, with Linux system, with a access RADOS, access RADOS, and Swift and Swift kernel client and aa kernel client and Linux kernel client with support for with support for QEMU/KVM driver QEMU/KVM driver and support for C, C++, Java, C, C++, Java, FUSE Python, Ruby, Python, Ruby, and PHP and PHP RADOS RADOS A reliable, autonomous, distributed object store comprised of self-healing, self-managing, A reliable, autonomous, distributed object store comprised of self-healing, self-managing, intelligent storage nodes intelligent storage nodes
- 48. CLIENT CLIENT metadata 01 01 data 10 10 M M M M M M
- 49. M M M M M M
- 50. Metadata Server • Manages metadata for a POSIX-compliant shared filesystem • Directory hierarchy • File metadata (owner, timestamps, mode, etc.) • Stores metadata in RADOS • Does not serve file data to clients • Only required for shared filesystem
- 51. one tree three metadata servers ??
- 57. recursive accounting ● ceph-mds tracks recursive directory stats ● file sizes ● file and directory counts ● modification time ● virtual xattrs present full stats ● efficient $ ls alSh | head total 0 drwxrxrx 1 root root 9.7T 20110204 15:51 . drwxrxrx 1 root root 9.7T 20101216 15:06 .. drwxrxrx 1 pomceph pg4194980 9.6T 20110224 08:25 pomceph drwxrxrx 1 mcg_test1 pg2419992 23G 20110202 08:57 mcg_test1 drwxx 1 luko adm 19G 20110121 12:17 luko drwxx 1 eest adm 14G 20110204 16:29 eest drwxrxrx 1 mcg_test2 pg2419992 3.0G 20110202 09:34 mcg_test2 drwxx 1 fuzyceph adm 1.5G 20110118 10:46 fuzyceph drwxrxrx 1 dallasceph pg275 596M 20110114 10:06 dallasceph
- 58. snapshots ● volume or subvolume snapshots unusable at petabyte scale ● snapshot arbitrary subdirectories ● simple interface ● hidden '.snap' directory ● no special tools $ mkdir foo/.snap/one # create snapshot $ ls foo/.snap one $ ls foo/bar/.snap _one_1099511627776 # parent's snap name is mangled $ rm foo/myfile $ ls -F foo bar/ $ ls -F foo/.snap/one myfile bar/ $ rmdir foo/.snap/one # remove snapshot
- 59. multiple protocols, implementations ● Linux kernel client ● mount -t ceph 1.2.3.4:/ /mnt NFS SMB/CIFS ● export (NFS), Samba (CIFS) ● ceph-fuse Ganesha Samba libcephfs libcephfs ● libcephfs.so ● your app Hadoop your app libcephfs libcephfs ● Samba (CIFS) ● Ganesha (NFS) ceph-fuse ceph fuse ● Hadoop (map/reduce) kernel
- 60. APP APP APP APP HOST/VM HOST/VM CLIENT CLIENT RADOSGW RADOSGW RBD RBD CEPH FS CEPH FS LIBRADOS LIBRADOS A bucket-based A bucket-based A reliable and fully- A reliable and fully- A POSIX-compliant A POSIX-compliant A library allowing A library allowing REST gateway, REST gateway, distributed block distributed block distributed file distributed file apps to directly apps to directly compatible with S3 compatible with S3 device, with aaLinux device, with Linux system, with aa system, with access RADOS, access RADOS, and Swift and Swift kernel client and aa kernel client and Linux kernel client Linux kernel client with support for with support for QEMU/KVM driver QEMU/KVM driver and support for and support for C, C++, Java, C, C++, Java, FUSE FUSE Python, Ruby, Python, Ruby, and PHP and PHP AWESOME AWESOME NEARLY AWESOME AWESOME RADOS RADOS AWESOME A reliable, autonomous, distributed object store comprised of self-healing, self-managing, A reliable, autonomous, distributed object store comprised of self-healing, self-managing, intelligent storage nodes intelligent storage nodes
- 61. why we do this ● limited options for scalable open source storage ● proprietary solutions ● expensive ● don't scale (well or out) ● marry hardware and software ● industry needs to change
- 62. who we are ● Ceph created at UC Santa Cruz (2007) ● supported by DreamHost (2008-2011) ● Inktank (2012) ● Los Angeles, Sunnyvale, San Francisco, remote ● growing user and developer community ● Linux distros, users, cloud stacks, SIs, OEMs http://ceph.com/
- 63. thanks BoF tonight @ 5:15 sage weil sage@inktank.com http://github.com/ceph @liewegas http://ceph.com/
- 65. why we like btrfs ● pervasive checksumming ● snapshots, copy-on-write ● efficient metadata (xattrs) ● inline data for small files ● transparent compression ● integrated volume management ● software RAID, mirroring, error recovery ● SSD-aware ● online fsck ● active development community