Re: [Bacula-devel] pivotal flow information

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Dear Fan,

let's sort some things out at the first step:

1. you're right: bacula currently only prepares vss backups on a "per
volume" mode. it does not care for, let's say sql .log/.mdf files. But vss
will automatically use the sqlserver-vsswrite to create a consistent state
for the shadow copy, if the volume to be backed up includes a .log/.mdf.

I think, this you figured out already yourself ;-)

2. backupread/write only cares for all ntfs-streams a file may contain. This
stream-system is similar to the fork files apple supports. *normally* a ntfs
file only contains 2 streams: detailed security information and the plain
content of the file. So backupread/write is a completely independent thing
in relation to vss.

3. the current restore process works without vss what is fine, because in
this (in comparison to backups rare) case, you can stop the software, so
that it leaves it fingers away from the file you want to replace. the you
don't need vss.

4. of course there are many scenarios, where vss restore *really* make
sense. in your case and when working with exchange for example!

OKay, so now you know why I didn't care for the vss restore but welcome your
work! I personally did closely follow the examples from the vss sdk. Then I
stripped some things, I didn't need, fighted with com and tested multiple
backupcalls until they worked....

Unfortunately I right now don't have the time to dig into this completely
together with you, but it may be that the "cocreatesecurity" or "init com"
and so on may be your problems. Please try the "restore" code from the vss
sdk examples. You'll *really* need it! did you already download them from
m$?

80004001 could mean 'not implemented'. If this is the case, again look into
the examples. one has to work differently on xp and windows 2003. The latter
one supports more...

Was this of help for you?

best,

thorsten

Thorsten Engel
>
> Thanks Kern!
>
> (I come from China, I am 23, my english may not well :) )

Well, my Chinese consists of reading about 3 or 4 characters :-)  I think we

can figure out what you mean.

I think I will let Thorsten answer, since I don't know much about vss.  I
will 
make a couple of notes below ...

>
> I just modified the part of vss code(/src/win32/filed/) and a little job.c
> (/src/filed/).
>
> In a backup task flow, I did (in ./src/win32/filed/vss_generic.cpp):
> 1). After BOOL VSSClientGeneric::Initialize(DWORD dwContext, BOOL
> bDuringRestore) function, I add a function and call it after Initialize().
> The function do add a component to Backup Components Document option. The
> component is a database message in sqlwriter Metadata Document. (I can
pass
> the GetWriterMetadata and other functions to get the parameters which the
> AddComponent() needs. and It is ok.)
> My sqlwriter Metadata Document content is(I added some blank line for
> readable): ----------------------------------------------
> <WRITER_METADATA xmlns="x-schema:#VssWriterMetadataInfo" version="1.0">
>
> <IDENTIFICATION writerId="a65faa63-5ea8-4ebc-9dbd-a0c4db26912a"
> instanceId="bf40ba33-7ae4-4fa2-bae6-3dd148ba396f"
> friendlyName="SqlServerWriter" usage="USER_DATA"
> dataSource="TRANSACTION_DB"/>
>
> <RESTORE_METHOD method="RESTORE_IF_CAN_BE_REPLACED" writerRestore="always"
> rebootRequired="no"/>
>
> <BACKUP_LOCATIONS>
>
> <FILE_GROUP logicalPath="FANXIAOGANG\SQLEXPRESS" componentName="master"
> restoreMetadata="no" notifyOnBackupComplete="yes" selectable="yes">
> <FILE_LIST path="C:\Program Files\Microsoft SQL Server\MSSQL.1\MSSQL\DATA"
> filespec="master.mdf"/>
> <FILE_LIST path="C:\Program Files\Microsoft SQL Server\MSSQL.1\MSSQL\DATA"
> filespec="mastlog.ldf"/>
> </FILE_GROUP>
>
> <FILE_GROUP logicalPath="FANXIAOGANG\SQLEXPRESS" componentName="model"
> restoreMetadata="no" notifyOnBackupComplete="yes" selectable="yes">
> <FILE_LIST path="C:\Program Files\Microsoft SQL Server\MSSQL.1\MSSQL\DATA"
> filespec="model.mdf"/>
> <FILE_LIST path="C:\Program Files\Microsoft SQL Server\MSSQL.1\MSSQL\DATA"
> filespec="modellog.ldf"/>
> </FILE_GROUP>
>
> <FILE_GROUP logicalPath="FANXIAOGANG\SQLEXPRESS" componentName="msdb"
> restoreMetadata="no" notifyOnBackupComplete="yes" selectable="yes">
> <FILE_LIST path="C:\Program Files\Microsoft SQL Server\MSSQL.1\MSSQL\DATA"
> filespec="MSDBData.mdf"/>
> <FILE_LIST path="C:\Program Files\Microsoft SQL Server\MSSQL.1\MSSQL\DATA"
> filespec="MSDBLog.ldf"/>
> </FILE_GROUP>
>
> <FILE_GROUP logicalPath="FANXIAOGANG\SQLEXPRESS" componentName="first"
> restoreMetadata="no" notifyOnBackupComplete="yes" selectable="yes">
> <FILE_LIST path="C:\Program Files\Microsoft SQL Server\MSSQL.1\MSSQL\Data"
> filespec="first.mdf"/>
> <FILE_LIST path="C:\Program Files\Microsoft SQL Server\MSSQL.1\MSSQL\Data"
> filespec="first_log.ldf"/>
> <FILE_LIST path="D:\sqlData" filespec="seconday.ndf"/>
> </FILE_GROUP>
>
> <FILE_GROUP logicalPath="FANXIAOGANG\SQLEXPRESS" componentName="second"
> restoreMetadata="no" notifyOnBackupComplete="yes" selectable="yes">
> <FILE_LIST path="C:\Program Files\Microsoft SQL Server\MSSQL.1\MSSQL\DATA"
> filespec="second.mdf"/>
> <FILE_LIST path="C:\Program Files\Microsoft SQL Server\MSSQL.1\MSSQL\DATA"
> filespec="second_log.ldf"/>
> </FILE_GROUP>
>
> </BACKUP_LOCATIONS>
> </WRITER_METADATA>
> ------------------------------------------------
> I just add the "second" database components message in the Backup
> Components Document. Not any other option.
> And after the backup finish, I saved the Backup Compoents doc and
sqlwriter
> Metadata doc.(After pVss->BackupComplete(&pAsync.p) completely in BOOL
> VSSClientGeneric::CloseBackup() do the save work.)
>
>
>
> My Backup Components Document content is:
> ------------------------------------------------
> <BACKUP_COMPONENTS xmlns="x-schema:#VssComponentMetadata" version="1.0"
> bootableSystemStateBackup="yes" selectComponents="yes" backupType="full">
>
> <WRITER_COMPONENTS instanceId="c4610868-5090-4af2-a0f7-9828e03c58fe"
> writerId="a65faa63-5ea8-4ebc-9dbd-a0c4db26912a">
> <COMPONENT logicalPath="FANXIAOGANG\SQLEXPRESS" componentName="second"
> componentType="database"/>
> </WRITER_COMPONENTS>
>
> </BACKUP_COMPONENTS>
> ------------------------------------------------
> Is the content right? It not include the restore method ?
>
> It can compile the bacula fd, and run it use enable_vss on, and can
> completely a backup task no error.

When Bacula does a backup, the data streams that Bacula writes are identical

with and without VSS.  With VSS, Bacula simply gets the file data from the 
snapshot (shadow copy) of the file rather than directly from the file using 
BackupRead().

During the restore, the data that was written during the backup is read,
then 
simply written to disk using BackupWrite().  No VSS is needed.

>
>
> 2). In the restore part, I added a new function in restore_cmd() which is
> in job.c. The insert Positon is after "do_restore(jcr)". I just want to
> test the vss restore now. The funtion main include :
> IVssBackupComponents::InitializeForRestore, (can get the backup compoents
> doc right)
> IVssBackupComponents::GatherWriterMetadata,
> IVssBackupComponents::SetSelectedForRestore, (can get the right parameters
> right, and the sqlwriter running ok)
> IVssBackupComponents::PreRestore,
> (copy the file to the original position)
> IVssBackupComponents::SetFileRestoreStatus,
> IVssBackupComponents::PostRestore,
> IVssBackupComponents::Release.

As I said, I am not a VSS expert, maybe Thorsten can explain.  However, if
you 
have read special backup data that is not read with BackupRead(), then you 
will need to write it to a different Bacula stream   (STREAM_....) .  Then 
when doing a restore, when that special stream is encountered you will need 
to use whatever techniques VSS provides for giving it back to the 
application.

>
> It can compiled the bacula fd right. But when running a restore task, The
> SetSelectedForRestore() return an error 80004001, and terminate.

I suspect that you never write the data out to the Bacula Volume during the 
backup procedure.  I suspect that VSS simply wrote the data somewhere to
disk 
and you must then read and write that data to the Bacula volume.  Thorsten 
can probably answer this better than I can.

> I am desponding. What's wrong with me? Would you give me some advices? or
> give me a vss restore simple code. The bacula not include the vss restore
?
> I referenced the betest and vshadow examples which is in vss sdk, But no
> idea. --------------------------------------------------------------

Hopefully the above will give you some ideas and that Thorsten can give you 
some more ideas ...

> Thank you very much!
>
>
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