On 09/12/2019 18.49, Dave Howorth wrote:
On Mon, 09 Dec 2019 18:36:48 +0100 Per Jessen <per@computer.org> wrote:
Dave Howorth wrote:
Interesting. I do use LVM so I could do the same. There's a good article at:
http://strugglers.net/~andy/blog/2017/07/19/bcache-and-lvmcache/
That seems to suggest it may be worth the extra effort of
configuring bcache IIUC. I might have a go with my new SSD; it seems like a sensible way to use part of it.
One difference seems to be that you can add an SSD cache to a populated LVM filesystem, whereas bcache needs you to create a new cached filesystem, I think.
The choice of lvmcache was easy - we're using lvm anyway (of course), and it was so easy to add to existing systems. I'm not sure exactly when we did it, it was at least a year ago. The SSD are relatively small - 240Gb I think. Not at all expensive either.
Given what the comments say about losing the entire filesystem if the cache drive dies, and inability to take backups, have you found any solutions?
The wikipedia mentions another type of bcache that is being developed, that works at the filesystem level instead of the device level (bcachefs). «History bcache was first announced by Kent Overstreet in July 2010, as a completely working Linux kernel module, though at its early beta stage.[7] The development continued for almost two years, until May 2012, at which point bcache reached its production-ready state.[4] It was merged into the Linux kernel mainline in kernel version 3.10, released on June 30, 2013.[8][9] Overstreet has since been developing the file system bcachefs, based on ideas first developed in bcache that he said began "evolving ... into a full blown, general-purpose POSIX filesystem".[10] He describes bcache as a "prototype" for the ideas that became bcachefs and intends bcachefs to replace bcache.[11] He officially announced bcachefs in 2015,[12] and as of 2018 has been submitting it for consideration for inclusion in the mainline Linux kernel.[13] » -- Cheers / Saludos, Carlos E. R. (from 15.1 x86_64 at Telcontar)