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FW: Estimating a database backup time during business hours

Mich Talebzadeh, on the Sybase Product Futures mailing list, wrote up a verbose introduction to his proposed dump database …. COMPRESSION = n ESTIMATE_ONLY feature.  Basically it would give an estimate of time that the backup will take.  In my opinion, it would be a useful feature but I can’t see how it would be implemented as the compressability of the data could radically differ.  The Z Library, like any other compression mechanism, has no concept of an estimated time for compressing the current data chunk let alone for the rest of the data stream.  If the backup server were to give an estimated time, it wouldn’t be even remotely accurate in most cases.  Kudos to Mich for proposing it though.  🙂

As we now have the capability to use archive database utility in ASE
12.5.4, the ability to interrogate and identify performance issues by
loading the problem database to archive DB is well in hand.

The question that comes to mind is the usual frequently asked question
during the middle of the trading day.

The users have identified a problem with trade capture. We need to
backup
the database, load it into a DEV server and quickly identify and fix
the
problem.

Technically nothing special about it. However, from a business point of
view it is highly visible as the business is impacted and few mangers
are involved including the DBA.

The DBA can give a guesstimate of how long is going to take to back up
the database. However, this is usually based on the overnight backups,
when the server is quiet.

Much like ‘kill SPID with statusonly’ that allows us to give an
estimate of how long is going to take for a rollbacked transaction to
complete, we also need the ability to give a fairly reasonable estimate
of how long is going to take to backup a large database and the
projected dump size, taking into account the load on ASE during the
business hours. This in my opinion is a feature that is desirable to
have.

DUMP DATABASE to ‘/dumpdevice/database_name.dmp’ WITH
COMPRESSION = n ESTIMATE_ONLY

This utility can also be used to estimate the timings of backups and
the
dump area size required on occasions when the OS or ASE is upgraded and
databases need to be backed up.

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Comments

  1. Most backup software titles, in addition to scheduled and on demand backups will have an estimation facility which allows you to establish the required backup window based on cpu power / availability, broadband, quantity and type of data. The crux of the issue is that many estimators take nearly as long as the actual backup procedure. The http://backupanytime.com estimator addresses this issue with intelligent prediction and local variable based formulae. The software is multiplatform and comes with extensive support.

    Robert

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