Re: hdd + ssd

[Stefan Ring <stefanrin@xxxxxxxxx>]

On Fri, Oct 23, 2015 at 1:48 PM, Emmanuel Florac <eflorac@xxxxxxxxxxxxxx> wrote:
> YMMV, but here's my take:
>
>  * flashcache being a facebook internal dev, probably is the most
>    largely deployed one. It's clearly production-ready.
>
>  * EnhanceIO works fine but I haven't tested it thoroughly. It adds no
>    signature to the drives so it can be added to existing filesystems
>    (flashcache and bcache need reformatting). However that means that
>    bad thing may happen if you're careless -- it's clearly targeted at
>    always-on servers.
>
>  * bcache works fine but the latest fixes haven't been backported, so
>    you should probably use it only with latest (4.2, 4.3) kernels. It's
>    not very mature yet but it's *friggin' fast*.
>
>  * dm-cache is the easiest to set-up with the lvmcache command (if your
>    distro is recent enough of course). Like very very easy. It's
>    unfortunately the slowest of the pack, apparently. Doesn't need
>    reformatting IF your existing FS already lives in a LV.

Very good summary, thanks! Do you also happen to know if all of these
retain cache contents across reboots?