FreeBSD restartable send/receive over WAN

[Adam Nowacki]

On 2017-02-26 15:08, Shiva Bhanujan wrote:
> The compression that we use on our ZFS filesystems is lz4.  So, if I have to pipe it through a compression algorithm, that'd be uncompressing and compressing it 4 times.
> 
> disk (lz4) -> zfs send (uncompress) -> compress (gzip) -> (network) -> uncompress (gzip) -> zfs recv (compress) -> disk (lz4)
> 
> isn't this quite expensive?  We have to transfer multi terabyte files on a WAN link.  I'm also of the understanding that gzip by itself is single-threaded, so that'd peg one of the CPUs to 100%.  there might be other compression algorithms that can be used, but sending the ZFS as it is compressed on the filesystem is something that would be optimal, and would reduce the overhead of the additional [de]compressions that are taking place?

Well, yes, there is more cpu work but also better compression ratio. It all depends on how fast you can actually transfer the data over that WAN link. xz -0 should consume 5-10MB/s of uncompressed data while compressing 2x better than LZ4.

> 
> 
> ________________________________________
> From: owner-freebsd-fs at freebsd.org [owner-freebsd-fs at freebsd.org] on behalf of Jeremy Faulkner [gldisater at gmail.com]
> Sent: Saturday, February 25, 2017 4:03 PM
> To: freebsd-fs at freebsd.org
> Subject: Re: FreeBSD restartable send/receive over WAN
> 
> Pipe it through a compressor
> 
> On 2017-02-25 2:09 PM, Shiva Bhanujan wrote:
>> Hi,
>>
>> I just tried restartable send/receive in 10.3 and it works like a charm.  I was wondering if compressed send has made its way into FreeBSD?  I checked 10.3 and 11.0-RELEASE, and I don't see the -c/--compressed option.  Any pointers?
>>
>> Regards,
>> Shiva