Caching

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



I have a couple of questions about caching:

I have 5 VM-Hosts serving 20 VMs.
I have 1 Ceph pool where the VM-Disks of those 20 VMs reside as RBD Images.

1) Can i use multiple caching-tiers on the "same" data pool?
   I would like to use a local SSD OSD on each VM-Host that can serve as "application accelerator" local-cache for the VM-Disks.
   I can imagine data corruption if other VM-Hosts write to the same Ceph data pool but not using the same caching-tier.
   I imagine no data corruption if i know no other VM-Hosts will access that Ceph object (VM-Disk / RBD image).
   I would need to flush the cache of that VM-Host when i shutdown the VM on it, before i can start the VM on a different VM-Host.
   Or is Ceph perhaps smart enough that it would notify the above Caching-Tier to evict a cached object when there is a change on that object not changed by that caching-tier?

2) RBD Cache is useless for hosting Oracle databases?
   If Oracle is doing a O_SYNC and RBD Cache would flush on O_SYNC, then there would be nothing cached. Correct?

3) Would a caching tier be smart enough to flush dirty/modified objects on "idle" i/o?
   (when client i/o is not busy ceph will use that time to sync to backend)
   I know it will flush on at a certain capacity (50%) or on a certain age (600sec), but can it also flush on a certain busy/idle percentage or auto-magically/intelligently?


Thanks,


Samuel Terburg
Panther-IT BV
www.panther-it.nl



_______________________________________________
ceph-users mailing list
ceph-users@xxxxxxxxxxxxxx
http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com

[Index of Archives]     [Information on CEPH]     [Linux Filesystem Development]     [Ceph Development]     [Ceph Large]     [Ceph Dev]     [Linux USB Development]     [Video for Linux]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]     [xfs]


  Powered by Linux