From mboxrd@z Thu Jan 1 00:00:00 1970 From: Roy Sigurd Karlsbakk Subject: Re: RAID performance - new kernel results Date: Tue, 16 Apr 2013 21:28:47 +0200 (CEST) Message-ID: <20372204.0.1366140527266.JavaMail.root@zimbra> References: <516C6018.5030800@turmel.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <516C6018.5030800@turmel.org> Sender: linux-raid-owner@vger.kernel.org To: Phil Turmel Cc: linux-raid@vger.kernel.org, Adam Goryachev List-Id: linux-raid.ids > > I suspect that the single ping packets being lost are an indication > > of a > > problem, but this should not impact the users (TCP should look afte= r > > the > > re-transmission, etc). Wether this is related to the longer 10-50 > > second > > outage I'm not sure. >=20 > No, single lost pings are *not* a sign of a problem. It is perfectly > normal for a network to have random traffic spikes that fill a > switch's > store-and-forward buffers. ICMP pings are *datagrams*, like UDP, so > they aren't retransmitted when dropped. Losing them as infrequently a= s > you say suggests your network isn't heavily loaded. Switches (unlike bridges) do not use store-and-forward. They use cut-th= rough, meaning they use store-and-forward for the initial packet from A= to B and then store the path and switch it later, sniffing the MAC add= resses and just use pass-through. As was said, the traffic on the network was minimal, so I really doubt = this had an impact. Getting 30 seconds+ of drops must come from a bad n= etwork stack or a really bad switch, but then again, two switches were = tested, so I doubt the switches alone could do that. What may be doing it, is bad (or perhaps incompatible) bonding setup. Vennlige hilsener / Best regards roy -- Roy Sigurd Karlsbakk (+47) 98013356 roy@karlsbakk.net http://blogg.karlsbakk.net/ GPG Public key: http://karlsbakk.net/roysigurdkarlsbakk.pubkey.txt -- I all pedagogikk er det essensielt at pensum presenteres intelligibelt.= Det er et element=C3=A6rt imperativ for alle pedagoger =C3=A5 unng=C3=A5= eksessiv anvendelse av idiomer med xenotyp etymologi. I de fleste tilf= eller eksisterer adekvate og relevante synonymer p=C3=A5 norsk. -- To unsubscribe from this list: send the line "unsubscribe linux-raid" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html