Return-Path: X-Original-To: apmail-cassandra-user-archive@www.apache.org Delivered-To: apmail-cassandra-user-archive@www.apache.org Received: from mail.apache.org (hermes.apache.org [140.211.11.3]) by minotaur.apache.org (Postfix) with SMTP id 8240E6A52 for ; Tue, 12 Jul 2011 15:02:26 +0000 (UTC) Received: (qmail 17557 invoked by uid 500); 12 Jul 2011 15:02:23 -0000 Delivered-To: apmail-cassandra-user-archive@cassandra.apache.org Received: (qmail 17437 invoked by uid 500); 12 Jul 2011 15:02:22 -0000 Mailing-List: contact user-help@cassandra.apache.org; run by ezmlm Precedence: bulk List-Help: List-Unsubscribe: List-Post: List-Id: Reply-To: user@cassandra.apache.org Delivered-To: mailing list user@cassandra.apache.org Received: (qmail 17429 invoked by uid 99); 12 Jul 2011 15:02:22 -0000 Received: from nike.apache.org (HELO nike.apache.org) (192.87.106.230) by apache.org (qpsmtpd/0.29) with ESMTP; Tue, 12 Jul 2011 15:02:22 +0000 X-ASF-Spam-Status: No, hits=-0.7 required=5.0 tests=FREEMAIL_FROM,RCVD_IN_DNSWL_LOW,SPF_PASS,T_TO_NO_BRKTS_FREEMAIL X-Spam-Check-By: apache.org Received-SPF: pass (nike.apache.org: domain of s5alye@gmail.com designates 209.85.210.172 as permitted sender) Received: from [209.85.210.172] (HELO mail-iy0-f172.google.com) (209.85.210.172) by apache.org (qpsmtpd/0.29) with ESMTP; Tue, 12 Jul 2011 15:02:16 +0000 Received: by iye7 with SMTP id 7so5720499iye.31 for ; Tue, 12 Jul 2011 08:01:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type:content-transfer-encoding; bh=ltWVHqyuljLPwli4c2aogeRLdFd6UFEnJVOdWj6Hy4I=; b=DQBqWufrad71m6kn86ADmE+q44E6ULfvaPFPf7uL2WCEqb6N6fMRCYUByRJOAXoOY0 /Zoa2Jgs1St6em/TWJZq1BuvtXcy4Mcethw6nysGoOKEI681LGkJHEfUwxForyjU2kP2 Yi6fx26L82euXyOIXd+RpmY3LfgyhtxBQ88yU= MIME-Version: 1.0 Received: by 10.42.150.8 with SMTP id y8mr6633909icv.471.1310482915111; Tue, 12 Jul 2011 08:01:55 -0700 (PDT) Received: by 10.231.37.137 with HTTP; Tue, 12 Jul 2011 08:01:55 -0700 (PDT) In-Reply-To: References: <189C3828-FA2D-4F0E-902A-3E84FC1E110D@gmail.com> Date: Tue, 12 Jul 2011 11:01:55 -0400 Message-ID: Subject: Re: Meaning of 'nodetool repair has to run within GCGraceSeconds' From: A J To: user@cassandra.apache.org Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: quoted-printable X-Virus-Checked: Checked by ClamAV on apache.org Just confirming. Thanks for the clarification. On Tue, Jul 12, 2011 at 10:53 AM, Peter Schuller wrote: >> From "Cassandra the definitive guide" - Basic Maintenance - Repair >> "Running nodetool repair causes Cassandra to execute a major compaction.= .... >> During a major compaction (see =93Compaction=94 in the Glossary), the >> server initiates a >> TreeRequest/TreeReponse conversation to exchange Merkle trees with neigh= boring >> nodes." >> >> So is this text from the book misleading ? > > It's just being a bit less specific (I suppose maybe misleading can be > claimed). If you repair everything on a node, that will imply a > validating compaction (i.e., do the read part of the compaction stage > but don't merge to and write new sstables) which is expensive for the > usual reasons with disk I/O; it's "major" since it covers all data. > The data read is in fact used to calculate a merkle tree for > comparison with neighbors, as claimed. > > -- > / Peter Schuller >