Displaying 2 results from an estimated 2 matches for "rbd_cache_block_writes_upfront".
2019 Jul 29
3
Why librbd disallow VM live migration if the disk cache mode is not none or directsync
...or VM migration, if the cache
implementation guarantees that cache invalidation and disk write are
synchronous operations.
For example, I'm using Ceph RBD images as VM storage backend. The Ceph
librbd supports synchronous write-through cache, by setting
rbd_cache_max_dirty to zero, and setting
rbd_cache_block_writes_upfront to true, thus it would be safe for VM
migration. Is that true? Any suggestion would be appreciated. Thanks.
Ming-Hung Tsai
2019 Jul 29
0
Re: Why librbd disallow VM live migration if the disk cache mode is not none or directsync
...implementation guarantees that cache invalidation and disk write are
> synchronous operations.
>
> For example, I'm using Ceph RBD images as VM storage backend. The Ceph
> librbd supports synchronous write-through cache, by setting
> rbd_cache_max_dirty to zero, and setting
> rbd_cache_block_writes_upfront to true, thus it would be safe for VM
> migration. Is that true? Any suggestion would be appreciated. Thanks.
The commit you refer to is very old and my hunch is that things looked
different in 2012. Things might have changed since then and if
write-through wasn't safe ~7 years ago, it mi...