Flashbackup backups data by reading block after block (physical order). If a
file is not stored in consecutive blocks on disk it will not be stored in
consecutive blocks on tape. If you restore such a file the data has to be
collected from different positions of a tape or, even worst, from different
positions on multiple tapes. That of course leads to slower file restores,
although NetBackup does a great optimization job on that.
This disadvantage is as bigger as more fragmented your data on disk is.
On the other hand, if you need to restore the whole disk it will be much
faster, because you read consecutive disk blocks from tape and there is
nearly no disk positioning necessary.
Ueli Schweizer
CTO
AGITE Software AG · Boesch 43 · CH-6331 Huenenberg · Switzerland
Direct: +41 79 204 9190 · Phone: +41 41 781 5678 · Fax: +41 41 781 5677
Ueli.Schweizer AT AGITE-Software DOT com · http://www.AGITE-Software.com
backupVISUAL?...
...we make life on backup easy
-----Original Message-----
From: veritas-bu-bounces AT mailman.eng.auburn DOT edu
[mailto:veritas-bu-bounces AT mailman.eng.auburn DOT edu] On Behalf Of dy018
Sent: Wednesday, July 02, 2008 11:33 AM
To: VERITAS-BU AT mailman.eng.auburn DOT edu
Subject: [Veritas-bu] NBU Flashbackup vs Normal Backup
Thanks everyone for your input.
BTW Ueli, can i ask you abt slow restore. You mention for single file
restore require various tape positioning, meaning to restore 1 file, it need
to position the tape afew time before restoring the entire file? whereas a
normal filesystem backup when retore a single file only require 1 time
postioning? So the multiple times taken for the positioning wil affect the
overall restore timing?
Ueli Schweizer wrote:
> Data fragmented on disk will also be backed up fragmented using
Flashbackup.
> The restore of single files will be slower in this case, because the
> data cannot be restored without various tape positioning.
>
> Ueli Schweizer
> CTO
>
> AGITE Software AG 7 Boesch 43 7 CH-6331 Huenenberg 7 Switzerland
> Direct: +41 79 204 9190 7 Phone: +41 41 781 5678 7 Fax: +41 41 781
> 5677 Ueli.Schweizer < at > AGITE-Software.com 7
> http://www.AGITE-Software.com
>
> backupVISUAL...
> ...we make life on backup easy
>
>
> -----Original Message-----
> From: veritas-bu-bounces < at > mailman.eng.auburn.edu
> [mailto:veritas-bu-bounces < at > mailman.eng.auburn.edu] On Behalf Of
> dy018
> Sent: Wednesday, July 02, 2008 5:02 AM
> To: VERITAS-BU < at > mailman.eng.auburn.edu
> Subject: [Veritas-bu] NBU Flashbackup vs Normal Backup
>
>
> Hi,
>
> Recently i was told by symantec that using Flashbackup to backup the
> raw device will greatly increased the backup and restore time.
>
> After reading through the admin guide abt the advanced client, i also
> understand that flashbackup also able to do file level restore instead
> on restoring the entire volume which i initially tot is going to be
> the trade off.
>
> This spark a question, so a flashbackup is almost the same as a normal
> file level based backup which also able to retore individual files,
> wat are the cons of using flashbackup beside higher cost to buy the
> advanced client licenses? Anyone here knows the pros and cons?
>
> Regards
>
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