On Wed, Jul 2, 2014 at 3:06 PM, Marc <mail at shoowin.de> wrote: > Hi, > > I was wondering, having a cache pool in front of an RBD pool is all fine > and dandy, but imagine you want to pull backups of all your VMs (or one > of them, or multiple...). Going to the cache for all those reads isn't > only pointless, it'll also potentially fill up the cache and possibly > evict actually frequently used data. Which got me thinking... wouldn't > it be nifty if there was a special way of doing specific backup reads > where you'd bypass the cache, ensuring the dirty cache contents get > written to cold pool first? Or at least doing special reads where a > cache-miss won't actually cache the requested data? Yeah, these are nifty features but the cache coherency implications are a bit difficult. More options will come as we are able to develop and (more importantly, by far) validate them. -Greg > > AFAIK the backup routine for an RBD-backed KVM usually involves creating > a snapshot of the RBD and putting that into a backup storage/tape, all > done via librbd/API. > > Maybe something like that even already exists? > > > KR, > Marc > _______________________________________________ > ceph-users mailing list > ceph-users at lists.ceph.com > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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