From user-return-18461-apmail-cassandra-user-archive=cassandra.apache.org@cassandra.apache.org Wed Jul 6 05:52:42 2011 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 D5D9E6CBB for ; Wed, 6 Jul 2011 05:52:41 +0000 (UTC) Received: (qmail 35191 invoked by uid 500); 6 Jul 2011 05:52:39 -0000 Delivered-To: apmail-cassandra-user-archive@cassandra.apache.org Received: (qmail 34430 invoked by uid 500); 6 Jul 2011 05:52:25 -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 34420 invoked by uid 99); 6 Jul 2011 05:52:16 -0000 Received: from athena.apache.org (HELO athena.apache.org) (140.211.11.136) by apache.org (qpsmtpd/0.29) with ESMTP; Wed, 06 Jul 2011 05:52:16 +0000 X-ASF-Spam-Status: No, hits=2.2 required=5.0 tests=HTML_MESSAGE,SPF_PASS X-Spam-Check-By: apache.org Received-SPF: pass (athena.apache.org: local policy) Received: from [122.224.216.65] (HELO hzvscan2.utstar.com.cn) (122.224.216.65) by apache.org (qpsmtpd/0.29) with ESMTP; Wed, 06 Jul 2011 05:52:09 +0000 Received: from CNMAIL13.cn.utstarcom.com (cnmail07.cn.utstarcom.com [172.18.22.157]) by hzvscan2.utstar.com.cn (8.13.8/8.13.8) with SMTP id p665pdpb015632 for ; Wed, 6 Jul 2011 13:51:40 +0800 Received: from CNMAIL12.cn.utstarcom.com ([172.18.22.156]) by CNMAIL13.cn.utstarcom.com with Microsoft SMTPSVC(6.0.3790.3959); Wed, 6 Jul 2011 13:51:39 +0800 Content-class: urn:content-classes:message MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----_=_NextPart_001_01CC3BA0.C619FCC4" X-MimeOLE: Produced By Microsoft Exchange V6.5 Subject: memory Date: Wed, 6 Jul 2011 13:51:46 +0800 Message-ID: <7DA4B654C7FEB24C9998EE4867BEE93EBC7C13@CNMAIL12.cn.utstarcom.com> X-MS-Has-Attach: X-MS-TNEF-Correlator: Thread-Topic: memory Thread-Index: Acw7oMqt0tmLB76bRninBm+xsWl8Jg== From: "Donna Li" To: X-OriginalArrivalTime: 06 Jul 2011 05:51:39.0458 (UTC) FILETIME=[C64C0A20:01CC3BA0] This is a multi-part message in MIME format. ------_=_NextPart_001_01CC3BA0.C619FCC4 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable All: For a rough rule of thumb, Cassandra's internal datastructures will require about memtable_throughput_in_mb * 3 * number of hot CFs + 1G + internal caches.=20 =20 Why cassandra need so much memory? What is the 1G memory used for? =20 =20 Best Regards Donna li ------_=_NextPart_001_01CC3BA0.C619FCC4 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

All:

For a rough rule of thumb, Cassandra's = internal datastructures will require about memtable_throughput_in_mb * 3 * number of hot CFs + 1G + internal caches.

 

Why cassandra need so much memory? What is the = 1G memory used = for?

 

 

Best Regards

Donna li

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