AButters (17th March 2014)
We have just had an issue with our SAN and as a result or Veeam Backups failed at the weekend which is when they are set to run a synthetic full. Anyway I am looking at changing our backup to tape and did a little more reading on Veeam but I think I've managed to confuse myself on the Veeam forums and wanted to check that I'm not doing something which I shouldn't be.
Currently our backups run a synthetic full at the weekend and transform previous full backup chains into rollbacks to save space. Now I've read that as this relies on the previous incremental/rollbacks being good you could end up in a situation where (if used for a long time) the synthetic full may contain corrupt data. So should I be using the Perform Active full backup option as currently I've been relying on the Synthetic fulls to created our Full backup.
One consideration I've got is should I be running an Active Full once a month to limit any corruptions? We are trying to reclaim some space on our servers by performing some archiving but until this is done if I need to run Active Full Backups I am going to start running out of space!! But equally I don't want to rely on Synthetics if they shouldn't be relied upon long term. Can anyone clarify if I need to run Synthetics & Active Full?
AButters (17th March 2014)
From the recommendations I've read, Synthetic Full backups are fine, but as you mention if a corruption/problems rolls it's self into the backup then the synthetic will keep that defect within it - the last recommendation I saw on the Veeam forum was every 1 - 3 months setup the job to automatically perform an Active Full backup to ensure that a fresh, full backup is taken without faults (But I manually run it every so often to manage the space as I haven't got enough currently like you).
To be honest, this wasn't explained to me at the time and for nearly a year we were running Synthetic backups until I started to question why one backup group was so large when I'd removed a load of VM's out of it. Turned out it was because our setup was set not to remove VM's nolonger backed up until an Active Full was performed.
penfold (18th March 2014)
We tried synthetic full like you on a weekly schedule and although during the week days the backups were fast at the weekend the synthetic full was taking 48 hours plus to complete or sometimes failing altogether. We then went back to reverse incremental, it's slower on average but still completes all our backups within our backup window, takes less space and you always have a latest full backup so recovery should be faster.
I'd look at why the backup was corrupted in the first place and fix that first.
We don't have an issue with synthetic fulls taking too long (well it seems the only time is due to an issue with our VM). But I was more concerned about keeping backups as synthetic fulls thinking all was well only to discover that our backups become useless due to a corruption being rolled into a full backup. I think I may need to start looking at performing Active Full's but not sure where I'm going to find the space from to be honest!!
I changed our backups from Incremental with synthetic fulls to reverse incremental and have not looked back, these are all backed up to our 100TB backup SAN and then off to tape from there. I managed to save approx 35TB off the Backup SAN and therefore able to increase our restore points on the File servers to over 3months allowing for instant file recovery of any deleted/lost data within 5minutes.
Again instant VM recovery is a breeze and works a treat.
zag (19th March 2014)
Yeh we do Reverse Incremental as well onto 1tb of SSD disk.
I now have 60 work day restore points on our main file server so we can go back nearly 3 months to restore any file in seconds.
We did have to increase memory on our backup server/Veeam proxy as reverse incremental is quite IOP intensive but overall the space saving was worth it. Like I said we have 90+ days on fileservers along with 90+ days on exchange we can then do quarterly archiving from disk to tape and just checked we still have 28TB to increase further if required.
So does reverse incremental save space then? I thought it would still require the same storage space as Full+ Incrementals but it wasn't recommended if backing up to tape? I'm just trying anything
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