1. SANtopia Design Features 컴퓨터. 소프트웨어연구소

2. 자료저장시스템워크샵 배경  인터넷의 확산으로 인한 데이터의 폭발적 증가  대용량 저장장치의 요구사항 증가  확장 (Scalability) 가능한 저장매체 필요 Source: IDC (PetaBytes) (Years) 저장매체 용량의 수요예측

3. 자료저장시스템워크샵 배경  기존 서버 중심 환경의 문제점  성능상의 문제 발생 ( Performance Bottleneck )  확장성의 한계 ( 저장장치, 컴퓨팅 파워 ) Application Server DB Server Client Internet Web Server 기존에 사용되던 서버 중심 저장장치 환경

4. 자료저장시스템워크샵  SAN 기반 저장장치  수 많은 저장장치를 고속의 전용 네트워크 (Fiber Channel) 에 연결하여 대용량의 공유 저장매체를 제공하는 새로운 개념의 저장장치 Internet Storage Area Network Web Server Appl. Server DB Server FC Switch Client RAID Tape Driver RAID Disk FC Switch 배경

5. 자료저장시스템워크샵 배경  SAN 의 수요 확대  년 평균 증가율 : 85%  스토리지 수요 증가율 (87%) 과 비슷한 증가율 Source: IDC (Millions of $) (Years) SAN(Storage Area Network) 시장 예측

6. 자료저장시스템워크샵 배경 SAN 은 대용량 저장장치를 지원하기 위한 새로운 개념의 저 장장치 H/W 기술 SAN 하드웨어 기술 - 데이터 공유 - 성능 병목 해결 - 사고 발생시 복구 - 통합 관리 SAN 의 가치를 더욱 높이기 위해서는 SAN Virtualization 을 지원하는 시스템 소프트웨어가 제공되어야 함 대용량 공유 파일 시스템의 지원 H/W 독립적인 논리적 저장장치 지원 중앙집중식 시스템 매니지먼트 지원 - 대용량 저장 매체 지원 - 저장장치 확장성 지원 추가 요구사항

7. 자료저장시스템워크샵 배경  SAN Virtualization 시장 예측  SAN H/W 증가율보다 높은 증가율을 나타냄 (100% 이상 )  SAN Virtualization 시장규모는 SAN H/W 의 10% 수준 Source: IDC (Millions of $) (Years) SAN Virtualization 시장 예측

8. 자료저장시스템워크샵 SANtopia 란 ?  S/W to provide SAN Virtualization High Performance Fast Accessible Directory Structure Load Balancing Global Buffer Sharing High Performance Fast Accessible Directory Structure Load Balancing Global Buffer Sharing High Availability Fast recovery Online backup Snapshot High Availability Fast recovery Online backup Snapshot SAN Infrastructure SAN Infrastructure Shared File System Shared File System Logical Volume Driver Logical Volume Driver System Management System Management SANtopiaSANtopia High Scalability Dynamic Inode - No preallocated inode table Dynamic Reconfiguration - Online Resizing High Scalability Dynamic Inode - No preallocated inode table Dynamic Reconfiguration - Online Resizing

9. 자료저장시스템워크샵 Features of SANtopia  64-bit File and File System  Global File Sharing  Provide Global buffer  Open SAN File System  Storages Cluster File System  Centralized Lock Manager with Load Balancing  Not use device lock  Integration of Buffer Manager and Lock Manager  Software RAID(0, 1, 0+1, 5, Concatenate)  Comprised of three parts  Logical Volume Manager  Global Shared File System  Lock and Buffer Manager

10. 자료저장시스템워크샵 SANtopia 구조 Disk File Manager Global Lock & Buffer Manager VNODE Interface System Call Interface IP over SAN SCSI over SAN Mapping Management Configuration Management Logical Volume Manager System Management Performance Monitor Online Backup Scalability Management I/O Management Mapping Management Inode Management Log Management Recovery Management BitMap Management Transaction Management File Operation Management IP over SAN

11. 자료저장시스템워크샵 SANtopia Logical Volume Manager

12. 자료저장시스템워크샵 Features of LVM  Volume Create/Remove  On-line Volume Resize  Dynamic Reconfiguration  Software RAID(0, 1, 0+1, 5, Concatenation) disk1 disk2 disk3 disk4 disk5 disk6 disk7 disk8 Volume 1 : Striping (RAID 0) Volume 2 : Concatenation Volume 3 : Striped parity (RAID 5) Volume 4 : Striped Mirroring (RAID 0+1)

13. 자료저장시스템워크샵 A Disk Layout label Private partition (physical partition ) Public partition (physical partition)  Logical Partition Information  Disk Identifier  Information about Logical Volume Allocation Bitmap Mapping Info. Logical partition

14. 자료저장시스템워크샵 Volume Resize  Extend/Shrink Unit = Logical Partition  When a Volume is Striped Add Row Add Column Data Relocation Needed

15. 자료저장시스템워크샵 Free Space Manager  Physical Allocation Bitmap  Divide into fixed size units  Each unit controlled by separate locks  Entire bitmap is duplicated  Effects  Increase Parallelism  Get scalability  Avoid bottleneck  Reduce metadata search time physical allocation bitmap Logical partition

16. 자료저장시스템워크샵 Mapping Manager  Virtualization of Physical Storage  provide flexibility  enable data movement between Logical Partitions  enable snapshot  Each Mapping Information  Covered by one host  Chained declustered for safety  Same effects as Free Space Manager  Flexible to fail-over Host C Logical partition Host D Logical partition Host A Logical partition Host B Logical partition

17. 자료저장시스템워크샵 I/O Manager  Load Balancing of I/O  Read Policy  Round-Robin Policy §In case of same Capability  Preferred-Plex Policy §In case of different Capability

18. 자료저장시스템워크샵 SANtopia File Manager

19. 자료저장시스템워크샵 Features of SANtopia File Mgr  Extent Based 64-bit File System  64-bit Address  Support Large File  Dynamic inode allocation  Multi-Level inode  Support Large Directory  Extensible Hash based directory management  Fast Recovery  Metadata Journaling  Inode Stuffing

20. 자료저장시스템워크샵 SANtopia File System Layout Boot Super Allocation Blocks Extent Block Block (inode, directory, data block) Bitmap 0 2 64 -1  Extent based allocation  Super Block : SANtopia file system information  Allocation Block  No preallocated area for inode, directory entry, data block  Extent based allocation (4KB ~ 64KB)  Extent bitmap  Located end of address space(file system size)  Need to distinguish from object type in Extent Allocation Bitmap  Use 2 bit : 00 – not used,01 – inode 10 – dir entry,11 – data block

21. 자료저장시스템워크샵 inode  Dynamic allocation inode  No limitation of inode number  No preallocated inode area  Cf) ext2 file system : 1 node per 4KB  Each inode size is 1 extent  Fragmentation  Stuffed inode for space efficiency  64-bit inode number  Using unique ID in SANtopia inode number (inode information) file or directory information Data Block Pointer or Stuffed Data Extent

22. 자료저장시스템워크샵 inode structure Dinode Info. Double Indirect blocks : Extent Single Indirect blocks …… …  Dynamic Multi-Level Inode Allocation

23. 자료저장시스템워크샵 Directory(Extendible Hash) Dir Info. 00 01 10 11 0000 0001 0010 0011 0100 0101 0110 0111 1000 1001 1010 1011 1100 1101 1110 1111 Director y Node (Extent) Indirec t hash root hash 2 4

24. 자료저장시스템워크샵 Recovery  Journaling 기법 사용  Write in-core log buffer to log-disk when metadata updates.  Log disk is circular buffer  Metadata modification operations(transaction)  create, remove, unlink, link, allocation, truncate, rename, … Log Transaction Manager Transaction Manager Recovery Manager Recovery Manager Log Manager Log Manager Metadata Manager Metadata Manager Metadata File Operation (transaction) System Manager (system recovery)

25. 자료저장시스템워크샵 SANtopia Buffer and Lock Manager

26. 자료저장시스템워크샵 Features of Buffer Manager(I)  Support Global File Sharing  Reduce disk I/O  Sharing each buffer  Split distributed BM  GBM are distributed(partitioned) on several nodes  Manage Global Buffer List and Local Buffer List  Communication vs. Space overhead  Manage the logical global buffer  Weak correctness of global buffer list  Safe but not up-to-date

27. 자료저장시스템워크샵 Features of Buffer Mgr(II)  Integration of buffer and lock message  Overlapped with global lock manager  Piggyback the buffer lists over lock messages  Reduce the number messages  Adopt write invalidation scheme  For the sake of simplicity  Support buffer forwarding scheme  Enlarging the performance by reducing the disk I/O

28. 자료저장시스템워크샵 Structure of Buffer Manager  Local and Global Buffer Manager  Decision of GBM : Inode hash

29. 자료저장시스템워크샵 Operations between GBM and LBM  Buffer list information  GBM Server Failure

30. 자료저장시스템워크샵 Features of Lock Manager  Lock Mode  Shred lock and Exclusive lock  Lock Object  64bits inode - File Lock  Distributed(partitioned) on several nodes  Host-based locking  Overlapped with global buffer manager  Global Lock Manager(GLM) vs. Local Lock Manager(LLM)  Delayed Lock Free  Callback scheme for lock free  Callback by lock server  No lock entrance after receiving a callback message  Recovery on host failure  I/O Fencing  Rebuild lock table: take locks from the failed host

31. 자료저장시스템워크샵 Integration of Lock Mgr and Buffer Mgr

32. 자료저장시스템워크샵 Operational Design(I) local buffer manager buffer … local lock manager local lock 1 …… local lock 2 … global buffer manager buffer … global lock manager host 1 …… host 2 … global lock 1 lock(lock_id,mode,local_buffer_list), unlock(lock_id,local_buffer_list) lock_grant( lock_id, mode, host_related_global_buffer_list) buffer forwarding call_back( lock_id, hrgbl) invalidate at unlock

33. 자료저장시스템워크샵 Operational Design (II)  Global Lock Manager  Upon receiving lock request  Update global buffer list using the local_buffer_list  Upon receiving unlock request  Grant lock before processing the unlock request  Update global buffer list using the local_buffer_list  Upon granting lock  Piggyback a part of global buffer list concerned with the host  Upon sending callback  Piggyback a part of global buffer list concerned with the host

34. 자료저장시스템워크샵 Operational Design (III)  Local Lock Manager  Upon sending lock request  Piggyback the local buffer list  Upon sending unlock request  Invalidate buffer related with the lock  Piggy back the local buffer list  Upon receiving lock grant  Save the piggybacked global buffer list  Upon receiving callback  Prohibit the lock counter from being increased  Unlock as soon as possible

35. 자료저장시스템워크샵 Operational Design (IV)  Local Buffer Manager  Upon receiving forward request  Send the requested buffer without validity check  Of course, check whether the requested block is still cached  If the buffer is already flushed, send an acknowledge signal