Afaik you can configure the use of an rbd device like below. 

- Am I correct in assuming that the first one is not recommended because 
it can use some caching? (I thought I noticed a speed difference between 
these 2, and assumed it was related to caching). 
- I guess in both cases the kernel module is used and same libraries are 
- Are there any other (dis)advantages?

1. via mapped rbd device
    <disk type='block' device='disk'>
      <driver name='qemu' type='raw' cache='writeback'/>
      <source dev='/dev/rbd/rbd/vps-test2'/>
      <target dev='vda' bus='virtio'/>
      <boot order='2'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x0c' 

2. direct 
    <disk type='network' device='disk'>
      <driver name='qemu' type='raw' cache='writeback'/>
      <auth username='rbd.vps'>
        <secret type='ceph' 
      <source protocol='rbd' name='rbd/vps-test2'>
        <host name='' port='6789'/>
        <host name='' port='6789'/>
        <host name='' port='6789'/>
      <target dev='sda' bus='scsi'/>
      <boot order='1'/>
      <address type='drive' controller='0' bus='0' target='0' unit='0'/>

ceph-users mailing list

Reply via email to