Re: raid0 vs single, and should we allow -mdup by default on SSDs?

[Mitch Harder <mitch.harder@sabayonlinux.org>]

On Wed, May 7, 2014 at 3:52 AM, Marc MERLIN <marc@merlins.org> wrote:
> On Wed, May 07, 2014 at 09:29:41AM +0100, Hugo Mills wrote:
>> On Wed, May 07, 2014 at 01:18:40AM -0700, Marc MERLIN wrote:
>> > On Tue, May 06, 2014 at 07:39:12PM +0000, Duncan wrote:
>> > > That appears to be a very good use of either -d raid0 or -d single, yes.
>> > > And since you're apparently not streaming such high resolution video that
>> > > you NEED the raid0, single does indeed give you a somewhat better chance
>> > > at recovery.
>> >
>> > zoneminder saves 'video' as a stream of independent small jpegs, so I'm
>> > good. Actually come to think of it they're so small that they probably
>> > all ended up in the raid1 metadata. That also means that I'm not getting
>> > twice the storage space like I planned to. Oh well...
>>
>>    There's a mount option to change the threshold at which files are
>> inlined in metadata: maxinline=<bytes>. You could play with that for
>> this particular use-case.
>
> Oh cool, thank you.
>

Since each non-inlined file will occupy a minimum of 4k, you may find
that inlining will still save space even if it is duplicated.

Even if they are duplicated in the metadata under RAID1, inlining a
bunch of 256 byte files will still be more space efficient than
storing them as regular files.

But if most of the files are in the 2k-3k range, you may be more
efficient to store them as files.