1、,VSS和Exchange的备份恢复,Windows存储系统系列课程,喻 勇, PMP/MCSE 微软特约讲师 讲义下载：,Windows存储系统系列课程,12月06日 Windows存储系统架构和基本概念 12月14日 Volume Shadow Copy和存储备份新技术 12月23日 Windows文件系统和NTFS 12月27日 企业级存储技术对比和案例分析 1月12日 VSS和Exchange的备份恢复 1月16日 Windows Virtual Disk Service,http:/ 常规备份的类型和缺陷 磁盘快照技术 VSS和Exchange 2003 What can VSS
2、backup and restore? VSS components how do they work? VSS events Caveats and considerations,Exchange数据库的工作方式,数据库事务日志的作用 永远不要删除日志文件 万不得已不要启动循环日志 日志和数据库放在不同的磁盘阵列上 浅谈 Exchange Server邮件存储系统-原理篇 http:/ APIs Called,ESE Backup Mode,Begin Backup, Backup tells store backup will begin Type of backup, Store inf
3、orms ESEand backup mode entered, Agent requests DB pagessequentially Pages are check-summedas read,End Backup, Page read completed Logs copied to tape Logs Deleted Backup set closed,ESE Normal Mode,Backup Complete,恢复所用数据集,E2K恢复过程,Dismount Database,ESE Restore Mode,Begin Restore,End Restore,ESE Norma
4、l Mode,Restore Complete, Backup application or Administrator dismounts database, Store informs ESE andrestore mode entered Restore SG created, Agent copies EDB/STM from Tape to DB path Log files from backup set are copiedTo temp restore location PAT files copied from backup set toTemp location, PAT
5、file processed byESE restore instance Logs are processedBy ESE restore instance Current logs processedBy ESE restore instance Cleanup/Restore SG killed, DB is mounted by SG Data deleted from temporary directory,常规备份技术的局限性,对生产系统的磁盘I/O有一定的影响 恢复的时间比较长,What is a shadow copy?,Known in the industry as “sn
6、apshots” Infrastructure for creating a point-in-time copy of a single volume or multiple volumes Appears static, even though the original data is changing,t1,t0,t2,Back up the static shadow copy while,Create a shadow copy,Data is written to the disk,Write some data,Snapshot type clone,Make a complet
7、e copy of entire volume up front: Clone the volume. Break off the clone.Pro Very fast after split Best practice clone has better disaster protection than copy on write Cons Requires n+1 clones to support n hot snaps Takes time to synchronize clone,Snapshot type copy-on-write,“”,Recover old view (t1)
8、 by laying snapshot side store over current data, “ ,Copy replaced sectors to a side store,”,Sectors modified between time t1 and t2,Only copy changes made since snapshot Done as software (volume or file) filter or hardware Pro: rapid creation Cons: Overhead increases with use Not a completely redun
9、dant data set Not inherently fault tolerant,Hardware snapshot overview,Block Table,1,2,3,4,5,6,7,Copy of Block Table,5,2,Hardware snapclone overview,Block Table,1,2,3,4,5,6,7,Copy of Block Table,Hardware snapclone details,Upon normalization, have an exact point in time clone/plex EMC BCV is differen
10、t because it uses real-time normalization and supports block journaling Can be presented to host As a separate or replacement LUN With no reliance on source,Shadow copies transport Scenarios?,Easily transport data across SAN Create and export shadow copy of database Import data on second server for
11、data mining, backup, testing, and similar tasks Offload backups to another server Copy production database for testing Copy of data for quick restore,Shadow copies transport,Production server,Backup server,Storage arrays,VSS and Exchange 2003 VSS backup and restore,Two restore types: Point in time r
12、estore(Recovery is to time of backup) Roll forward recovery(Recovery is to time of failure) VSS can restore to: Same location Alternate forest and server,What can VSS back up and restore?,Backup choices Minimum selection is the storage group (SG) (to truncate log files) Can snap multiple storage gro
13、ups at the same time (best practice will be to snap individual SG) Restore choices Entire storage group Single database Multiple databases from a single SG,VSS components,Windows Server 2003 (VSS service and framework) Requestor Third-party backup applications NTBackup does not use VSS to back up Ex
14、change Writer Application-specific logic for participating in snapshot process, and restore/recovery Provider Third-party hardware control software Windows includes a software provider,Snapshot services,Windows Server 2003 storage stack,OEMs,Microsoft,Kernel Mode,Miniport(s),Miniport,Port,Disk,Tape,
15、Changer,Class,SCSIPort,Storport,IDEPort,User Mode,WMI,Removable Storage Manager (tape and optical media management),Virtual Disk Service (RAID, disk access, Enclosures),HW Providers,Volume Shadow Copy Service (Point-in-time copies),SW Provider,Writers,Requestors,Writers,HW Providers,SW Provider,iSCS
16、I Initiator,iSCSIprt,Multipath I/O,DSM,DSM,DSM,MS MPIO,Applications,VSS Partial list of requesters and providers Check with each vendor for support status for Exchange Server 2003 and product features,For a complete list of partners visit the following Microsoft Web site: http:/ requestors,VSS write
17、rs,VSS providers,Bringing VSS into the environment ExWriter.dll,Installed with Exchange 2003 Exwriter and file system allows for a completely safe snap During an extended snap: Clients may hour-glass during submits Outlook 2003 in cached mode experiences zero production impact,What happens during ba
18、ckup?,PrepareForBackup Storage Group Administration functions are prohibited PrepareForSnapshot Volume dependencies are checked Freeze Flush current log file generation to disk Suspend writes to log files and .edb file Streaming (.stm) file will not be allowed to grow Read-only acces still allowed T
19、haw New log file generation is created Jet calls allow writes to log files and .edb file The .stm file allowed to grow OnBackupComplete Requestor validates Shadow Copy image consistency with ESEUTIL Log files are truncated Storage Group Administration functions resume,What happens during restore?,Ad
20、min takes affected storage groups offline (Vendors may with CDOEXM) Data restored to production location Either through storage device volume surfacing or streaming of content back into place Storage Group: writer leaves checkpoint file from backup Database: writer deletes current production checkpo
21、int file Starting Storage Group invokes hard recovery (Exchange views as typical power failure recovery),Details from ExWriter,Turn up Diagnostics Logging,Inspecting the backup metadata,VSS backup Finer points,RTM Exchange 2003 supports full backups and copy backups Log buffers flushed; new E00.log
22、file created, but checkpoint not advanced All databases must be mounted to purge logs Requestor needs to spawn ESEUTIL /K on snapped database for integrity check VSS sets snapped LUN to read-only and can only be made read/write by using calls to VDS,VSS restore Finer points,VSS backup requires VSS r
23、estore ExWriter sanity checks Whether databases are dismounted Circular logging state Dismount all databases in SG to restore entire SG or single MDB Requestor must contain BreakSnapshot API and VDS functionality to perform a LUN replace with a VSS restore,VSS Things to consider,Snapshot is not a co
24、mplete backup replacement but an alternative to streaming Makes sure requester does page check summing to identify corruption Not all snapshot solutions are equal Pure copy-on-write solutions assume streaming to tape or disk immediately Should still archive snaps,VSS Caveats,ExWriter unaware if mult
25、iple SGs on same LUN Mandatory verification of snapshot consistency Must restore to same logical drive letters No native support for VSS restores to RSG (third parties are working on this) Cannot mix Shadow copy and legacy streaming backups Cannot start another snapshot until BackupComplete is calle
26、d,Additional resources,822896, Exchange Server 2003 Data Back Up and Volume Shadow Copy Services http:/ (Hotfix) 833167, A Volume Shadow Copy Service (VSS) update package is available for Windows Server 2003 http:/ 825088, How To: Use the Eseutil Utility to Detect File Header Damage in Exchange 2003
27、 http:/ 833805, TechNet Support WebCast: Emerging enterprise storage technologies in http:/ 303949, How to restore an information store database in a clustered Exchange http:/ resources (2),“Using Exchange Server 2003 Recovery Storage Groups” white paper: http:/ DF144AF6-BEE5-4B35-866A-557E25FE2BA1
28、For a complete list of partners, visit http:/ Microsoft storage Web site http:/ /default.mspx Volume shadow copy overview: http:/ /datacenter/proddocs/en-us/Default.asp?url=/resources/documentation /WindowsServ/2003/datacenter/proddocs/en-us /ntbackup_backup_snapshot.asp (Note that the URLs should b
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