technical track-afterimaging progress database
TRANSCRIPT
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Progress Progress Database Database Repair & Repair & RecoveryRecovery
Dan Foreman
United Systems, Inc.
Email: [email protected]
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Introduction- Dan Foreman• Progress user since 1984 (V2.1)
• Guest speaker at every USA Progress Users Conference from 1990 to 1998
• Quest speaker at QAD Conference: 1997, 1999-2001
• Author of:
• Progress Performance Tuning Guide
• Progress Database Administration Guide (Nov 2001)
• Progress Virtual System Tables
• Progress V9 Database Administration Jumpstart
• A paper purchase now allows free online access
• ProMonitor - Performance Monitoring Tool
• ProD&L - Accelerated Dump/Load Utility
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Introduction - Who Are We?• BravePoint Inc. (www.BravePoint.com)• Formerly United Systems, Inc.• 125+ Employees• Three of us have used Progress since 1984• Progress Service Provider
• Performance Tuning• Database Administration and Recovery• Progress Training• Internet, Webspeed, Java• Custom Programming Services
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Introduction - Who Are You
• Progress Version: V6, V7, V8.2, V8.3, V9
• Unix? NT? Is there anything else?
• Largest Single Database?
• Highest User Count?
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Special Request
• Phasers on Stun• Isn't it interesting that the Microsoft
spell checker can’t find the word “Phaser”
• Cell Phones on Mute Please!
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Goals
• Can I teach you database brain surgery in only one hour?
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Preventative Maintenance
• Backups (yes, I know you’ve heard of them but have you tested them recently?)
• Test your Entire Recovery Plan• Warm Spare Database - A database on another
machine with a recent copy of the production DB This is easy to do in Progress...covered soon
• Unix: don’t logon as root unless you really need to• Use O/S security to protect the DB, BI, and AI files
from accidental/casual/intentional deletion
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Preventative Maintenance• Unix: Don’t use kill -9 to terminate a Progress
session; You might bring the database DOWN! if you kill a session that is holding a Latch
• Always have an up-to-date Structure (.st) file available
• Make sure your Sequences are not about to overflow (at approx. 2 billion)
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Preventative Maintenance• Monitor the BI file High Water Mark to avoid the 2gb size
limit bug which will corrupt your DB (_dbstatus-bisize Virtual System Table); not using VSTs? Turn Them On!• Monitor 'Delinquent' Transactions (transactions longer than 30-
60 minutes)• Monitor Large Transactions (-L Overflow)
• longtrx4.p Progress program on the BravePoint website to Automatically disconnect Delinquent Transactions
• Use the V8.3 -bithold parameter as an extra safeguard; Set to 999 or less; Set even in V9
• V9 supports Terabyte sized BI Files
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Preventative Maintenance
• Monitor the database High Water Mark to avoid growing into the Variable Length Extent
• Could hit the 2gb size limit
• Unbuffered I/O to the Variable Extent
• Sync call issued each time the Extent grows
• Size is requested from the OS in increasingly larger chunks (16-128 DB Blocks)
• Could run out of disk space
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Quiz Question
• Who are the Smartest People in the Room?
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Answer
• Those running After Imaging on their Mission Critical Databases
• Or stated in another way, if you’re not using AI, you shouldn’t be responsible for your company’s databases
• If your company can’t afford to lose a day’s worth of data you Absolutely need After Imaging
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After Imaging• Who is currently using After Imaging?• If no, why not?• The PSC documentation says it offers protection against
media failure• Disk fails 5 minutes before the backup starts on the
final day of your year end close• No paper trail• Ouch! Time to work on your resume (C.V.)
• After Image File(s) + Last (Good) Backup = State of DB at time of crash
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After Imaging - Why Use It?
• But you say…”I have disk mirroring (also known as RAID 1) so I’m protected against a disk failure”
• BUT Mirroring does NOT protect against all database evils
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After Imaging - Why Use It?
• True Horror Story #1
• A DBA FTP’d a test database into the directory where the production database resided... unfortunately they had the same name
• Disk Mirroring worked just fine…..
• After Imaging would have probably saved the day
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After Imaging - Why Use It?
• True Horror Story #2
• A user ran an archiving program on live data that wasn’t ready to be archived
• Once again the mirroring performed perfectly
• After Imaging might have improved the situation as it is possible to Roll Forward to a specific point in time
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After Imaging - Why Use It?• True Horror Story #3 • BI file hit the 2GB bug (true even with MV BI files) @ 4PM on a
busy day (300+ users)• 10GB Database was corrupted• Progress Tech Support Recommendation: dump & load or
restore from backup which meant substantial down time or data loss
• Fortunately the customer called me and I was able to temporarily patch the database
• I had recommended AI to this customer over one year prior to this event
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After Imaging - Why Use It?• Avoid the Problems related to probkup online
• Transaction Activity is Frozen while the BI File is Backed Up
• The Buffer Cache is "polluted" with Database Blocks that may not be Commonly Accessed
• The Overhead of Running a Streaming Tape Drive on the Same Machine as the DB
• Possible Solution
• Backup the AI Files
• Restore/Copy to Another System (or disk)
• Apply the AI Files (Roll Forward)
• Backup the Replicated Database
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After Imaging - Why Use It?• Easy generation of a Warm Spare DB
• A Warm Spare DB is:
• A standby database
• On another machine
• That can be brought online quickly in case of failure to the production system
• It’s ‘warm’ because it is not 100% current
• A HOT spare is not possible using AI but is possible using Replication Triggers
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Online Backup Warm Spare
Production
SystemWarm Spare
Production
DB
Warm Spare
DBAI Files
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After Imaging - Why Use It?
• Easy generation of a Report Server DB
• A Report Server DB is:
• A database on another system
• Used for reporting only
• To relieve the production system of the load imposed by reporting
• Doesn’t require same level of hardware or Progress license
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Preventative Maintenance
• Corruption Checks
• proutil dbanalys Blocks, Records, & Indexes
• probkup/procopyBlocks only
• proutil dbrpr Blocks and Records
• proutil dbscan Same as dbrpr (cmd line)
• proutil idxfix Indexes <-> Records
• Run periodically to make sure you don’t have hidden or unreported corruption
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Log File Checking• Check the Database log (.lg) file for errors DAILY. Look
for words such as:
• kill* drastic warn* error
system abnormal exceed* fail*
wrong unexpected*invalid died
damage* dead overflow* violation
fatal insufficient missing disappear* corrupt*allow* attempt* cannot
enough illegal impossible increase
unknown unable stop* beyond
• There are programs on the our Web Site to assist with log file checking or products such as ProMonitor
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1124 Errors
• SYSTEM ERROR: wrong dbkey in block…..• Indicates (with 99.9999% probability) a hardware problem• Don’t limit your search to disks; also consider: Disk
Controllers, SCSI termination, RAM (parity errors), Firmware, etc.
• Don’t Let the Hardware Technician Blame Progress or the Application
• Don’t let the Hardware Technician escape without solving the problem - every component might need to be swapped out
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Common Problems
• Corrupt Blocks
• Running out of disk space
• Deleted/Damaged Portion of the Database
• Database brought down by the Watchdog or the Broker itself
• Upgrade Progress (V7.3E with Patches, V8.2C with Patches)
• Use Loopback Client connections (-H & -S)
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Corrupt Blocks• What Kind of Block? Index or Data
• Block Type 2 (Index - IX) or 3 (Record Mgr - RM)• If IX block, try rebuilding the indexes• If RM block, consider the following
• Reformat a block as a Free block (proutil dbrpr)• Replace the block with the same block from another DB
(probably restored from a backup)• proutil dbrpr• 5. Dump Block (from the good database)• 4. Load Block (into the bad database)
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Emergency Dump• ‘Front and Back’ 4GL Dump
• for each customer by cust-num (until you hit the bad spot)
• for each customer by cust-num descending • If the Primary Index is Damaged, try Dumping using a non-
Primary Index• RECID Dump
• Doesn’t require an Index• Very Slow on a Large Database• Last Resort
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Miscellaneous Hints
• If you can’t get into the database with -F or any other way, try the Read Only (-RO) option
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Deleted Extents• First, backup the remaining pieces of the database • This may seem like a useless step but if your backup is
defective you may need to repair the broken DB and that’s difficult if it’s deleted
• The Backup gives you time to:• Prepare a plan of action• Call outside resources (like me) for help• Calm down• Lock your door• Prepare a new Resume (C.V.)
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Deleted AI Extents
• If an AI Extent is Deleted, simply disable AI and...
• What? You’re not running AI? BAD IDEA!
• Disable AI (rfutil aimage end)
• Fix the problem that caused the lost Extent
• Recreate the Extent with prostrct add
• Restart AI (rfutil aimage begin)
• If this doesn’t work, go to the next slide
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Deleted AI Extents• Disable AI with rfutil aimage end. You may get an error
message regarding the missing AI Extent but typically AI is still disabled
• Truncate the BI file with proutil truncate bi. You may get an error message regarding the missing AI Extent but typically the BI file is still truncated
• Remove all AI Extents with prostrct remove• Recreate the original AI Extents with prostrct add• Restart After Imaging with rfutil aimage begin• Reformat the truncated BI file with proutil bigrow
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Deleted BI Extents
• Force Access with -F• V8.2 and later -F only forces access on proutil
truncate bi• If you Force Access, consider the DB damaged!• Forcing Access THROWS AWAY the BI file• Forcing Access sets the ‘Tainted Flag’• Even if you fix the Tainted Flag, consider the DB
damaged!• Dump & Load (this is if AI is not enabled)
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Deleted DB Extents
• Restore the the DB and BI from Backup
• Apply the AI files
• Re-enable AI
• BI Grow
• Done!
• Still not running AI?, next slide please
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Deleted DB Extents
• Use prostrct unlock if the deleted Extent was Empty (above the High Water Mark)
• prostrct unlock will recreate missing Extents
• However unlock also changes the time stamps on the AI files and they can’t be used any longer
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Deleted DB Extents• Backup Extent Substitute
• This technique is for Extents that contain Data except the .d1 Extent (.d1 contains Master Block)
• Restore a copy of the deleted Extent from a Backup
• The Extent’s ‘Last Opened’ time stamps won’t match
• Use prostrct unlock to sync the time stamps (broken in V8.2 and V9)
• The data in the Extent might not match but…
• Use the -miracle option to re-create the Data
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Deleted DB Extents• If the database Broker is still running:
• DON’T Shutdown the Database
• That ‘closes’ the database extents and you won’t be able to re-open them
• If a Client is still attached to the DB and that Client can access the Progress Editor, simply Dump the Database from the Dictionary
• Even if they can’t get into the Editor, put dict.p (renamed as a menu item) into their PROPATH
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Deleted DB Extents - Unix
• Warm Boot the System Immediately
• Don’t Shut Down the DB First
• When Unix fsck runs, it will *probably* recover the deleted Extent
• Why?
• A file is not finally deleted until every process that has it open is gone (the Broker still has it open)
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Overlay Database• .db File is lost
• Create a Void Multi-volume Structure that matches the problem Database (hopefully you have a current .st file
• Take the .db from the Void Structure and use it for the problem DB
• Use prostrct unlock to Sync the Extent Timestamps
• The above steps apply if you are using probkup otherwise restore the .db from 3d party backup
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Overlay Database
• On V9 it is much easier to restore the .db file• prostrct builddb• Requires an up-to-date Structure File
(remember that from the Preventative Maintenance list?)
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Disk Full• Use prostrct repair to relocate Extents to a location
with more space• Copy the Extent• Create a new Structure File (.st) that reflect the
current location of the Database Extents (one good reason to have a current one)
• Run prostrct repair new.st• Done!
• There is a bug in prostrct repair. Don’t misspell the name of the Structure File or your .db file will vanish forever (fixed in V8.3C)
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BI Disk Full
• Do Not Run out of Space on the BI Disk if:• You can’t make more space for the BI file• You can’t relocate the BI file
• To Perform Crash Recovery, the BI file must grow• If there is no space for the BI file to grow, there is
no Crash Recovery• Force Access (-F) is the only option (if you don’t
have AI enabled)
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Progress HA Challenges
• Online Backups
• probkup online
• AI Backup (already covered)
• Split Mirror
• Multi-DB backups cannot be restored to exactly the same point in time unless you are using Two Phase Commit
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Online Backup Options• probkup online
• Transaction Freeze during BI Backup
• Usually High I/O Volume
• Only DB and BI are Backed Up
• Performs an AI Extent Switch
• If backup to disk, backup file can’t be greater 2gb (except on NT) until V9.1B
• Use the Volume Size (-vs) Parameter if backup file is greater than 2gb
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Online Backup Options
• Split Mirror Backup
• Quiet the DB with proquiet enable
• Break the Disk Mirror
• Unquiet the DB with proquiet disable
• Backup the Offline Mirror
• Resync the Mirrors
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Online Backup Options
• Split Mirror Backup
• Database is vulnerable during the backup unless you have triple mirroring or similar feature
• Resynchronization of the Disks can be a big Performance Problem
• Still Can’t Backup (and restore) Multiple DBs Simultaneously
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Progress HA Challenges• Schema Changes. It is not possible to make Schema changes online,
even in V9.1• Adding New Extents. It is not possible to add Extents online, even in
V9.1• The BI Notes counter is limited to 2 billion until V8.3D and V9.1C• Promon/VST Statistics. The numbers recorded by promon are limited
to 4 billion• Updating the Progress Version. It is necessary to shutdown the DB to
change Progress versions• The DB log (.lg) file is limited to 2gb. A system that runs for months
could approach this limit. There is no way to ‘truncate’ the log file online.
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Progress HA Challenges• Database Reorg. In V8 is possible to build indexes online. In V9 it
is possible move tables (and indexes) from one Area to another but the tablemove option has the following disadvantages:• The table being moved is EXCLUSIVEly locked for the duration
of the move.• Because the RECIDs will be different in the new Area, all
indexes on the table must be rebuilt.• The table is moved in one transaction. This means that the BI
file can grow quite large. If AI is enabled, the notes generated by the table move is written to the AI file the same way that other transaction related activities are
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Sources of Help• Progress Documentation• Progress Database Administration Guide• [email protected]• Progress Knowledgebase (techweb.progress.com)• My Home Number: 541-754-2116• My Mobile Number is: 541-829-7741
• For those weekend emergencies when you need expert assistance
• This is not a free call
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