From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from relay.sgi.com (relay1.corp.sgi.com [137.38.102.111]) by oss.sgi.com (Postfix) with ESMTP id 039D27CA1 for ; Wed, 22 Jun 2016 17:51:26 -0500 (CDT) Received: from cuda.sgi.com (cuda2.sgi.com [192.48.176.25]) by relay1.corp.sgi.com (Postfix) with ESMTP id AEB688F8033 for ; Wed, 22 Jun 2016 15:51:26 -0700 (PDT) Received: from ipmail06.adl6.internode.on.net (ipmail06.adl6.internode.on.net [150.101.137.145]) by cuda.sgi.com with ESMTP id Bd1YE2oCSHou6AB0 for ; Wed, 22 Jun 2016 15:51:18 -0700 (PDT) Date: Thu, 23 Jun 2016 08:51:17 +1000 From: Dave Chinner Subject: Re: xfs metadata overhead Message-ID: <20160622225117.GX12670@dastard> References: MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: xfs-bounces@oss.sgi.com Sender: xfs-bounces@oss.sgi.com To: Danny Shavit Cc: xfs@oss.sgi.com On Wed, Jun 22, 2016 at 06:58:16PM +0300, Danny Shavit wrote: > Hi, > > We are looking for a method to estimate the size of metadata overhead for a > given file system. > We would like to use this value as indicator for the amount of cache memory > a system for faster operation. > Are there any counters that are maintained in the on-disk data > structures like free space for examples? No. Right now, you'll need to take a metadump of the filesystem to measure it. The size of the dump file will be a close indication of the amount of metadata in the filesystem as it only contains the filesystem metadata. In future, querying the rmap will enable us to calculate it on the fly, (i.e. not requiring the filesystem to be snapshotted/taken off line to do a metadump). Cheers, Dave. -- Dave Chinner david@fromorbit.com _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs