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Snapshot client?

Created: 31 Aug 2013 | 12 comments

Hi, what is differences between 'snapshot client' backup and regular backup? In documentation there is written that snapshot client backup makes point-in-time presentation of drive and dont lock drive. So what? Any kind on backup, example standard or ms-windows also make point-in-time presentation and also dont lock drive. Microsoft integrated VSS never lock drive. And when I make regular standard backup with netbackup, then in client options I can choose to use VSS or symantec own open-file-provider. Also, with 'snapshot client backu' there is not possibility to save windows system-state. This is strange, because windows VSS always makes also system-state through VSS writers. And when I use Netbackup regular backup, then I can include system-state. But system-state can only made through VSS, so it is also made through snapshot. Where is the point of term "snapshot client"?

Operating Systems:

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rookie11's picture

 what is differences between 'snapshot client' backup and regular backup? In documentation there is written that snapshot client backup makes point-in-time presentation of drive and dont lock drive.So what? Any kind on backup, example standard or ms-windows also make point-in-time presentation and also dont lock drive 

snapshot client' backup -- u already mentioned takes snapshot then backup files and data.

Regular backup -- tries to backup files and data one by one. If it is inuse or accessed by some other program, it won't be backedup.

host properties -- master server-- client attributes--WOFB-----------------snapshot error control--------------------------                    option1 abort backup on error option 2 disable snapshot n continue.

havnot understood 2nd part of ur post. please elaborate.

Magnifico's picture

When I want to backup some example 2008 server operating system partition to be able to restore from CD, then what kind of backup I must use? Must I use this "snapshot" option in policy, or not "snapshot" option?

Yasuhisa Ishikawa's picture

BMR is only option that enable you to recover the host by CD/DVD boot. And BMR can not be enabled in snapshot client features. You need to configure regular backup on which all system drives are selected.

Authorized Symantec Consultant(ASC) Data Protection in Tokyo, Japan

Magnifico's picture

Then what kind of thing this "snapshot" is at all? When windows operating system is backed up, then it cant be done without point-in-time open-file service, like windows integrated VSS. VSS makes snapshots. What kind of things are then NetBackup 'snapshots'?

Yasuhisa Ishikawa's picture

"Snapshot Client" is not a backup method but set of features that works on conjunction with array-based snapshot technologies(e.g. EMC TimeFinder) and software snapshot provider(e.g. Veritas Storage Foundation). This is used for alternate client backup and point-in-time recovery. Please check doc below for more about snapshot client.

NetBackup 7.x Snapshot Client Compatibility List: http://www.symantec.com/docs/TECH126901
 
NetBackup Snapshot Client 7.5 Administrator’s Guide: http://www.symantec.com/docs/DOC5165

Windows Open File Backup feature in regular backup uses VSS, but it is not what snapshot client provides as this use case does not use alternate client and point-n-time recover from VSS snapshot. VSS snapshot in WOFB is created at the beginning of backup, and is deleted at the end of backup. it it is not kept persistently for point-in-time recovery.

Authorized Symantec Consultant(ASC) Data Protection in Tokyo, Japan

Magnifico's picture

Thanx, I readed documentation about snapshot-clients but still wasnt get the point. So, I understand that I just cant use "snapshot client" with just Windows operating system, without any additional software or hardware? Right?

Yasuhisa Ishikawa's picture

I assume major issue in this thread is whether you can use snapshot client to protect host operating systems - as wrote, it is not possible. When we checked 'Perform snapshot backup' in policy attribute, 'Collect disaster recovery information for Bare Metal Restore' become greyed out. Without BMR, you can not recovery system from CD.

Your understanding is almost right, but we can configure Snapshot Client with VSS method without any additional software or snapshot-capable array. We can use WIndow's bundled software VSS provider. However, we can not configure alternate client as snapshots created by this provide can not be accessed from other host. Instant Recovery(point-in-time recovery) for system drive is also not possible as (if it is allowed - I believe this sort of operation is probidden by OS) rollbackup from snapshots against running system leads system inconsistency. OS may crash if you do so.

Conclusion:

  • BMR is only option to recovery system from CD.
  • BMR is available only in regular backup.
  • VSS is used in regular backup for Windows Open File Backup feature, but it is not same with Snapshot Client.
  • We can configure Snapshot Client backup without additional software and arrays, but this is meaning less.

Authorized Symantec Consultant(ASC) Data Protection in Tokyo, Japan

Magnifico's picture

But I dont need CD or PXE to restore operating system. Example I can restore snapshot to some other drive and then copy it with Paragon Drive Manager to actual operating system drive or make backup from temporary drive with Acronis and restore it to actual operating system drive. The question is how good and reliable is this snapshot? Is it real open-file (also point-in-time) backup? Does it made SQL quiescent backup? Does it made ActiveDirectory database, COM and other Windows internal databases transactions quiescent backup? VSS does all this automatically. If it dont do quiescent backup, then it is still usable if it can make disks buffers flush and is smart enough to wait bigger disk inactivity hole before open-file backup operation. Once I tried it with master server backup and get file open errors. I dont know, wasnt it really able to open file or it was just because I made backup of master server (that is not allowed) and of course I wasnt installed some separate client (dont know from where to install it, maybe from the same package where other NetBackup server  installations.)............And the most important - is this kind of snapshot is file-based or sector-based? If it is sector-based, then Im very interested about it, because I dont trust file-based operating system backup. Now I use R1Soft for backing up servers and workstations operating system drives. And support this snapshot also incremental backups? Also I dont get is it only open-file provider/writer or it is some kind of replication? VSS is only open-file service. VSS dont replicate or copy partition. When sector write is detected, VSS copies this sector into hidden place and after that allows real sector copy from some software to real target. Backup software must itselt backup data. It can do sector-based backups or file-based backup. Windows internal backup is example sector-based. NetBackup regular backup, that uses windows VSS, is file-based. Backup software reads sectors or files from partition and if it reaches changed sector, then open-file service as VSS gives for backup software this sector that was previously copied into hidden place from VSS, instead of real sector. This gives exact point-in-time backup. But I dont have knowledge how this NetBackup snapshot-client works.   

Yasuhisa Ishikawa's picture

Your example of Paragon and Acronis is not same with what Snapshot Client intends to do. Snapshot of these software is temporary one and will be removed after backup. This use is same with that in regular backup with WOFB in NetBackup.

Snapshot use in Snapshot Client is;

* create temporary snapshot in conjunction with array-based snapshot provider to enable alternate client reading data at snapshot point from disk array(off-host backup)

* create persistent snapshot in conjunction with snapshot provider that can work with primary storage disks to recover data from persistent snapshots(Instant Recovey)

By the way, what do you want to do? System backup? Data Backup? If you are to backup both system drive and application data in single backup, you should not do so. this is common consideration in backup planning.

Authorized Symantec Consultant(ASC) Data Protection in Tokyo, Japan

Yasuhisa Ishikawa's picture

Say more to be close to behavior of NetBackup.

MS-Windows policy type(in both regular backup and Snapshot Client backup) is intended to protect files, and is not aware of consistency of applications. For example, even if WOFB is enabled(by default), SQL database files(*.ldf, *.mdf,*ndf) can not be backed up in MS-Windows policy while SQL Server is running. I don't know exactly, but I guess MS-Windows backup does not request VSS to include SQL Server VSS writer.

If you want to protect application data, you have to configure another policy with appropiate policy type like MS-SQL-Server.

Authorized Symantec Consultant(ASC) Data Protection in Tokyo, Japan

Magnifico's picture

I just need sector-level operating system backup, with incremental possibility, NTFS-journal support and windows system databases transactions quiescene. In snapshot-client documentation there is not sayed is it file-level or sector-level backup. Regular NetBackup backup is example file-level. There is many reasons why file-level backup is not reliable. Some software write into exact sector, write into hidden place, defragmenter utilities make optimization, etc. I find out Windows in-box VSS writers list - http://msdn.microsoft.com/en-us/library/windows/desktop/bb968827(v=vs.85).aspx#system_writer