From: "Dolev Raviv" Subject: RE: planning general storage capacity for y fs Date: Mon, 27 Apr 2015 10:55:51 +0300 Message-ID: <007201d080bf$96a0e4e0$c3e2aea0$@codeaurora.org> References: <006901d08012$3a1f97a0$ae5ec6e0$@codeaurora.org> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT Cc: , , "'Tanya Brokhman'" To: "'Richard Weinberger'" Return-path: Received: from smtp.codeaurora.org ([198.145.29.96]:42764 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752085AbbD0Hz4 convert rfc822-to-8bit (ORCPT ); Mon, 27 Apr 2015 03:55:56 -0400 In-Reply-To: Content-Language: en-us Sender: linux-ext4-owner@vger.kernel.org List-ID: >On Sun, Apr 26, 2015 at 1:14 PM, Dolev Raviv wrote: >> Hi, >> I'm looking for guidelines for planning storage capacity. I understand >> it strongly depended on the usage type. >> I want to know at what point storage fullness is effecting performance >> in a standard read/write partition. Do different File Systems >> (UBIFS/EXT4) have different full-free ratio? >> What about read only fs? Can I plan less free space in such cases? >> >> I'll appreciate any input on this, for UBIFS specific and fs in general. > >Not sure if I got your question. >You want to know how filesystems in general behave when they run out of free space? >The general answer is that they need more effort to find free space. > >In case of UBIFS you also have to think of the garbage collector. >See http://www.linux-mtd.infradead.org/doc/ubifs.html >At the end of the day you'll have to run benchmarks on your own to find out how a specific filesystem behaves on your workload... > Thanks Richard! Let me rephrase the question: In the past I knew there was a rule of thumb, 'leave free 30% of the storage space'. Nowadays I couldn't find any reference to this. I was wondering, is there a known point in UBIFS (or ext4), where leaving less free storage space, that performance is dropping? Maybe a ratio of free-occupied is not the right way to look at it, but to leave a certain size free (e.g. 50MB)? Thanks, Dolev -- Qualcomm Israel, on behalf of Qualcomm Innovation Center, Inc. Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project