From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kent Overstreet Subject: Re: Adding caching to existing volumes? Date: Thu, 24 Jan 2013 13:21:03 -0800 Message-ID: <20130124212103.GI26407@google.com> References: <20130122231547.GF26407@google.com> <12410785.14.1358961464521.JavaMail.root@zimbra> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <12410785.14.1358961464521.JavaMail.root@zimbra> Sender: linux-bcache-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Roy Sigurd Karlsbakk Cc: linux-bcache-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Steven Haigh List-Id: linux-bcache@vger.kernel.org On Wed, Jan 23, 2013 at 06:17:44PM +0100, Roy Sigurd Karlsbakk wrote: > > You've got to start from scratch, unfortunately. > > > > The reason is that there needs to be a bcache specific superblock on > > the > > backing device so bcache can keep the cache and backing device in sync > > - > > and especially so you can't accidentally mount and use the backing > > device without the cache. That would be bad. > > > > I just added an explanation to the faq - thanks for pointing it out. > > http://bcache.evilpiepirate.org/FAQ > > Then, what happens when the SSD dies? Formatting a backing device for bcache is separate from attaching it to a cache device - you can always run it in passthrough mode, and if the SSD dies while it's in use it'll automatically/transparently detach and switch to passthrough mode.