Am Mon, 15 Jul 2013 19:42:29 +0000 schrieb devel-request@xxxxxxxxxxxxxxxxxxxxxxx: > Message: 5 > Date: Mon, 15 Jul 2013 12:25:49 -0700 > From: Conrad Meyer <cemeyer@xxxxxx> > To: Development discussions related to Fedora > <devel@xxxxxxxxxxxxxxxxxxxxxxx> > Subject: Re: F20 System Wide Change: SSD cache > Message-ID: <20130715122549.5f14299b@m> > Content-Type: text/plain; charset=US-ASCII > > On Mon, 15 Jul 2013 13:57:39 -0400 > DJ Delorie <dj@xxxxxxxxxx> wrote: > > I think this is a bad idea, at least for my setup. I > > really don't want my small expensive boot SSD being beaten > > to death trying to cache a multi-terabyte array, especially > > since I have plenty of RAM that already serves that purpose > > (the machine rarely reboots). > > Actually, bcache is very good about *not* wearing out SSDs -- > it writes in giant erase block-sized portions and likely you > can tune how much is written. > > And either of these layers must be turned on by an admin -- > it's not going to be shoved down your throat. > > > At the very least, this feature should be disabled if the > > SSD is the boot/root drive. When SSDs fail, they fail > > completely, and it's irresponsible to cause early failure > > on a drive that's critical for booting and OS operation. > > 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.) > > > Also, I think such features should be postponed > > until/unless there's a clear and obvious way to > > configure/disable them that doesn't involve installing > > additional packages or editing obscure text files. > > Again -- no one is forcing you to use this. It's opt-in. > > Conrad Hmm, for me me this is more a question how can i configure bcache or dm-cache in a system which use more than one SSD and some conventional hard-disk. Seems like only you or some kernel devs know about how to do this. Can you give a configuration example for f19? For example, i use 4 SSD at a hardware-raid for my several systems (f17/f18/f19/rawhide), i called it A, i need this for testing compiz on baremetal for all current fedora releases. On a second hardware-raid- controller i have 4 conventional disks to store my data, i called it B. So, if i add another SSD for bcache or dm-cache, i called C, how can i configure it? 1. this configuration should not control disk A 2. disk C should use as cache for disk B Is this possible to configure? Do you have a link with more info's and configuration examples. best regards, Wolfgang -- devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxxx https://admin.fedoraproject.org/mailman/listinfo/devel
