Date: Tue, 11 Mar 2014 10:28:32 -0500 From: Danny Schales <dan@LaTech.edu> To: freebsd-stable@freebsd.org Subject: ZFS UNMAP performance Message-ID: <531F2BA0.6000105@LaTech.edu>
next in thread | raw e-mail | index | archive | help
This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --lemxcvxrNrOE5PIuu3aevs6BM6GheFRhf Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable I'm seeing very slow performance with certain operations on a ZFS filesystem built on ISCSI LUN's on a 10.0 system (new ISCSI implementation). The issue appears to be with BIO_DELETE operations. Monitoring the system with gstat shows expected times for read and write operations, but deletes are in the multiple hundreds of milliseconds under normal operation. Destroying a snapshot sends the times to astronomical levels. sysctl says the system is using UNMAP for deletes: kern.cam.da.0.delete_method: UNMAP I searched and found where Oracle issued a performance alert for Solaris 11.1 where ZFS using UNMAP was in use. Here's a link to a blog discussing it: http://schalwad.blogspot.com/2013/12/solaris-111-zfs-write-performance.ht= ml Is FreeBSD also impacted? If so, is there a fix or a workaround? Thanks Danny Schales --lemxcvxrNrOE5PIuu3aevs6BM6GheFRhf Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.22 (FreeBSD) iEYEARECAAYFAlMfK6AACgkQymYKbvs0SzFBkQCfUITyFSlvDqYD69EH1kXCFnj7 PisAni+7hyFoieLQCgO2omXEe1RVqG5/ =is8D -----END PGP SIGNATURE----- --lemxcvxrNrOE5PIuu3aevs6BM6GheFRhf--
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?531F2BA0.6000105>