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baber
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best backup type for time duration in backup and restore

Post by baber » Oct 14, 2017 9:20 am

Dear all
Hi

which of these backup type will be take more long time ???
i think reverse incremental will be take more than the other because first it will be take a diff backup and then it will be inject to the full backup
is that correct ????

1- forever forward incremental backup
2- forward incremental backup
3- reverse incremental backup

which of them will be take less time for recover ?????
i think reverse incremental will be take less time from other backups because just if recover full backup that is enough and is with latest changes
is that correct ????

BR

Andreas Neufert
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Re: best backup type for time duration in backup and restore

Post by Andreas Neufert » Oct 22, 2017 9:46 pm

Usually you will not see any real restore differences between them if your backup chain is not long.
The only real difference is how long Veeam need to bring the chain together before the first bit will be restored. Usually you will not notice that time.

A rule of thump is that you will notice the time when you go over 60 forward incremental on same full (no issue if you perform weekly or monthly synthetic or active fulls and 100 Reverse Incremental restore points.

Forward incremental backup with weekly synthetic fulls can be faster at full vm restore from very bad performing (non deduplication) storage. This is because syntetic fulls sort the data when it writes them and create a more sequential restore stream at full vm restore. Instant VM Restore, guest file restore and explorer based restores are not really faster as they read data randomly. A similar affect can be achieved with regular compact processing on a forever forward incremental backup.

Usually customer perform Forward or forever forward incremental backups to reduce VM snapshot livetime at backup and to reduce proxy task slot reservation time. Overall backup window is reduced with it.

baber
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Re: best backup type for time duration in backup and restore

Post by baber » Dec 30, 2017 6:09 am

thanks
you said Usually customer perform Forward or forever forward incremental backups to reduce VM snapshot livetime snapshot function in forever forward incremental backup and reverse incremental backup is the same almost why said usually customer perform Forward or forever forward incremental backups ?

BR

tdewin
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Re: best backup type for time duration in backup and restore

Post by tdewin » Dec 30, 2017 8:40 am

Snapshot time with reverse incremental can be up to 3x longer.

During the backup, forever incremental, it does 1 seq IO for every write to the incremental file. It is only after the backup is done, and the snapshot is removed that the merge start

Reverse incremental does 3 IO per write during backup. One to read the blocks that needs to be overwritten, one to write that block to the reverse increment and finally, the last IO to write the new block.

Andreas Neufert
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Re: best backup type for time duration in backup and restore

Post by Andreas Neufert » Dec 30, 2017 9:27 am

... and with Forever Forward Incremental the Proxy Task Slots are blocked not so long compared with Reverse Incremental. Therefore you can achieve a better backup window.

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