On Tue, 16 Jul 2013 10:36:55 +0200 Florian Weimer <fweimer@xxxxxxxxxx> wrote: > On 07/15/2013 09:25 PM, Conrad Meyer wrote: > > > By default, bcache runs a write-through cache -- it only > > caches clean data. If the caching SSD dies, the bcache > > layer can just forward requests to spinning drive. No > > data is lost. > > > > (Bcache has a writeback mode where data loss is possible. > > I do not recommend this mode.) > > What's the benefit of bcache, compared to just sticking > more RAM in the machine? That you can get more cache, > especially on systems that are short on memory sockets? Or > that the cache persits across reboots (something that can > be tricky because it requires synchronizing writes to the > cache and the disk)? >From 5 minutes of research: - 512 GB SSD on newegg -- $390. - 512 GB of RAM on newegg -- $4200*. * Doesn't include the cost of a server board that has 32 ram slots. So bcache is a more cost-effective way (than RAM) to expand the working set of disk you can access very quickly. bcache in write-back mode must persist or else you suffer data loss on any power failure. So, I think that answers that question. Getting the syncing right isn't actually that hard. Regards, Conrad -- devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxxx https://admin.fedoraproject.org/mailman/listinfo/devel
