From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?ISO-8859-1?Q?=C9tienne?= BERSAC Subject: dm-cache caching network volume Date: Tue, 18 Jun 2013 11:32:52 +0200 Message-ID: <1371547972.6128.8.camel@expiron> Reply-To: device-mapper development Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============6743504841615577598==" Return-path: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com To: dm-devel@redhat.com List-Id: dm-devel.ids --===============6743504841615577598== Content-Type: multipart/signed; micalg="pgp-sha1"; protocol="application/pgp-signature"; boundary="=-u83p5oP2xjTp2pYJzo8l" --=-u83p5oP2xjTp2pYJzo8l Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Hi, I'm testing dm-cache for using a local SSD as a cache for a network volume. My goal is to test dm-cache behaviour when network is down. The device is shared through iSCSI. The first test is filling a huge file with dd from /dev/zero. So, this is sequential access. While dd is running, i remove the tun iface from the bridge on the host. iSCSI properly detects the network failure. I expected dm-cache to continue filling dirty blocks, even if the network device is blocking. But it doesn't. The status shows that dirty blocks count stays the same. dd is blocking. I'm wondering if there is some cache desactivation due to sequential_threshold. But increasing sequential_threshold did not help. Where does dm-cache blocks ? Is it possible to have dm-cache "bufferize" blocks for network failures ? Regards, --=20 =C3=89tienne BERSAC NON STOP Systems --=-u83p5oP2xjTp2pYJzo8l Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iQEcBAABAgAGBQJRwClEAAoJEF5WQ9pdAIwZPJsH/3DmIaSvcjTjiPMJT6mrJG1K jbp4kqWiFBv6Ihc/LBJwXi8zPwMsaQTFkuxJOUCGhcASliU3JOwXXR2Sr3FJn7Vs J2Qw7tu5Md7irvvEX1Bd9QoT1v1+vgDKSIzawr5sVIuRQ8bpc4sL0lM57m/xf/AJ t9xExlHbt+zJqC8DNxRvL4V4BYIW5n/gABR1OfOVBaCusmKZdJGFZPyGcp9K2I+4 CY5u5sOAchr8GXMmAuQk9aBu/2wxX8fLQqyVJ+Vp5TCaSleuaZktm/x+W/OrZ6zm /bnueT0ElUkm/Axg39ceaiIV9UZGeceIzVHxK4sogn07P9Gs/EkssepYcDaY2C8= =Fs+T -----END PGP SIGNATURE----- --=-u83p5oP2xjTp2pYJzo8l-- --===============6743504841615577598== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline --===============6743504841615577598==--