[OpenIndiana-discuss] Antwort: Transferring everything in one zpool to be a, subtree in another larger zpool (Hans J. Albertsson)

Timothy Coalson tsc5yc at mst.edu
Tue May 5 20:36:07 UTC 2015


If you transfer many snapshots, especially if some are small, there is a
benefit from buffering: the receive end, after each snapshot, stops
consuming data, possibly for several seconds.  Without a buffer, this will
stall the sending side, so that nothing gets done during those pauses.  I
have put a small buffer on the sending side and a larger buffer on the
receiving side (as ssh is my current bottleneck, from encryption as you
note, but it is fairly close to the network speed anyway), and it helps get
things finished faster.

Tim


On Tue, May 5, 2015 at 8:32 AM, Doug Hughes <doug at will.to> wrote:

> you can also use ttcp or iperf just fine. I do that all the time and they
> are pretty much available anywhere. (ttcp is so simple it's just a single
> .c source file). The buffering isn't really the important part, using as
> close to raw tcp transport gets you the biggest benefit (vs
> encryption/decryption overhead and slowdown).
>
>
> Sent from my android device.
>
> -----Original Message-----
> From: "Hans J. Albertsson" <hans.j.albertsson at gmail.com>
> To: Discussion list for OpenIndiana <openindiana-discuss at openindiana.org>
> Sent: Tue, 05 May 2015 9:31
> Subject: Re: [OpenIndiana-discuss] Antwort: Transferring everything in one
> zpool to be a, subtree in another larger zpool (Hans J. Albertsson)
>
> mbuffer isn't included in FreeNAS.
>
> It IS available for FreeBSD, but I don't know if that version will
> behave responsibly in FreeNAS.
>
> FreeNAS devs say "mbuffer won't be included in FreeNAS because we
> already do proper buffering via dd."
>
> Would dd work for buffering in Solaris/OI??
>
> On 2015-05-05 14:26, Sebastian Gabler wrote:
> > Am 05.05.2015 um 14:00 schrieb
> > openindiana-discuss-request at openindiana.org:
> >> As a side note; just piping to ssh is excruciatingly slow, using netcat,
> >> "nc", speeds things up at least 4fold.
> > The method that worked fine for me was using mbuffer. (I couldn't make
> > netcat work, shame on me, but I also remember that there were several
> > pros of using mbuffer. I think one of them was the ability to use
> > digest to secure the transfer.)
> >
> > See:
> >
> http://everycity.co.uk/alasdair/2010/07/using-mbuffer-to-speed-up-slow-zfs-send-zfs-receive/
> >
> > That being said, it's exactly two years when I last did a migration
> > with zfs send | zfs receive. I hope that still works.
> >
> > BR,
> >
> > Sebastian
> >
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>
>
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