[OpenIndiana-discuss] Switching from lzjb to lz4 compression

[Gary Gendel]

On 06/26/2013 04:16 PM, Jim Klimov wrote:
> On 2013-06-26 22:01, Gary Gendel wrote:
>> Hi,
>>
>> Can I switch from one algorithm to another on the fly?  I assume that
>> only newly written data will be affected, but can the system deal with a
>> mixed compression pool?
>
> I believe it should be same as other compression algorithms
> (though may be more complicated due to use of feature flags).
> It was generally true that compression, checksums, copies and
> such write-time attributes are basically applied per-block at
> the time of write (i.e. if you zfs-send an uncompressed dataset
> and zfs-receive it into a compressed target dataset, the newly
> written blocks will be compressed).
>
> It is not a problem to have different algorithms (including
> "none"/"off" values) to be mixed in a single dataset, and of
> course quite possible to mix them in a pool.
>
> Another matter is the rpool dataset - it should use those algos
> which are added into GRUB support so it can mount the root.
> I believe LZ4 is among these (for source code versions of the
> illumos-gate which offer LZ4 integration altogether).
>
> HTH,
> //Jim Klimov
Jim,

Thanks.  That was what I thought based upon my recollection but I just 
couldn't find it documented.

Gary