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> differential scans was really poor Do you remember the details? First time I hear of something like this. Re: RCT - I read up on it a while back and the ove
by apankrat 7y ago
> differential scans was really poor
Do you remember the details? First time I hear of something like this.
Re: RCT - I read up on it a while back and the overall impression I got was that it was an application-level re-implementation of NTFS write change journaling. So filed it under 'exotics' and moved on.
Skimmed through the specs again now and I think that it's a good feature to have. Basically, RCT gives the program a change list for a VD for free IF it knows how to retrieve it. I made a note, will see what I can do. Thanks for the nudge.
- AaronFriel 7y agoThe full scan of say, a production database server's VHD negatively impacted performance to an unacceptable degree. It's something that probably could have been fixed with a more powerful storage subsystem. RCT not only gives the change list, but I believe it also ensures that on a cluster shared volume (CSV) there is an easy way to safely get the changed blocks. Normally a VSS operation on a cluster shared volume puts the drive into redirected mode, in which all IO has to go through the host that owns the CSV at that time. That also negatively affects performance, effectively limiting throughput to whatever the network speed is instead of the usually much faster SAS bus.
- apankrat 7y agoOK, thanks. The second part is something that I, not being a practicing sysadmin, have zero insight into. Very helpful. Re: full scan issues - that's likely due to bvckup2 being too aggressive with the IO. This is something that's easy to change [1], though I realize it's not a very good excuse and it should not require manual tweaking to begin with. [1] https://bvckup2.com/wip/01082018 https://bvckup2.com/wip/01082018
- AaronFriel 7y agoThanks for doing this thread, and kudos for shipping a good product!