Re: Suggestions for building new 44TB Raid5 array

[Marc MERLIN <marc@merlins.org>]

On Mon, Jun 13, 2022 at 02:21:07AM +0500, Roman Mamedov wrote:
> On Sat, 11 Jun 2022 07:52:59 -0700
> Marc MERLIN <marc@merlins.org> wrote:
> 
> > On Sat, Jun 11, 2022 at 02:30:33PM +0500, Roman Mamedov wrote:
> > > > 2) echo 0fb96f02-d8da-45ce-aba7-070a1a8420e3 >  /sys/block/bcache64/bcache/attach 
> > > >    gargamel:/dev# cat /sys/block/md7/bcache/cache_mode
> > > >    [writethrough] writeback writearound none
> > > 
> > > Maybe try LVM Cache this time?
> >  
> > Hard to know either way, trading one layer for another, and LVM has
> > always seemed heavier
> 
> I'd suggest to put the LUKS volume onto an LV still (in case you don't), so you
> can add and remove cache just to see how it works; unlike with bcache, an LVM
> cache can be added to an existing LV and then removed without a trace, all
> without having to displace 44 TB of data for that.

Thanks. I've always felt that LVM was heavyweight and required extra
steps and tools, so I've been avoiding it, but maybe that wasn't
rational.
bcache by the way, you can set it up without a backing device and then
use it normally without the cache layer. I think it's actually pretty
similar, but you have to set it up beforehand (just like LVM)

Marc
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