From owner-freebsd-fs@freebsd.org Thu Jul 26 05:23:34 2018 Return-Path: Delivered-To: freebsd-fs@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id C6EE8103FBC1 for ; Thu, 26 Jul 2018 05:23:34 +0000 (UTC) (envelope-from wlosh@bsdimp.com) Received: from mailman.ysv.freebsd.org (mailman.ysv.freebsd.org [IPv6:2001:1900:2254:206a::50:5]) by mx1.freebsd.org (Postfix) with ESMTP id 57D0E7E4BF for ; Thu, 26 Jul 2018 05:23:34 +0000 (UTC) (envelope-from wlosh@bsdimp.com) Received: by mailman.ysv.freebsd.org (Postfix) id 1BFA3103FBC0; Thu, 26 Jul 2018 05:23:34 +0000 (UTC) Delivered-To: fs@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id EE251103FBBF for ; Thu, 26 Jul 2018 05:23:33 +0000 (UTC) (envelope-from wlosh@bsdimp.com) Received: from mail-it0-x233.google.com (mail-it0-x233.google.com [IPv6:2607:f8b0:4001:c0b::233]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 780027E4BE for ; Thu, 26 Jul 2018 05:23:33 +0000 (UTC) (envelope-from wlosh@bsdimp.com) Received: by mail-it0-x233.google.com with SMTP id w16-v6so1149639ita.0 for ; Wed, 25 Jul 2018 22:23:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bsdimp-com.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=5ZbuzWFb05kcCtlP0k1Tn6UvFIbchDgGdXuKBUi7hyI=; b=o8rUa5YFxLD+0aj2P4oBe9GBNWMyYBo3lwxqizv1tGcfhegCTF+uBNLBq0vXaWi9z1 Mc/op+2C9qAY2N7ZbHpTEoqLT4B5EVKmoWycMhzPVURUX7y+/1lM844vGuEUHLulDdzd YRDMCk7ycQTwjkdI3HU3RU3Vg5s8eUmX78BoykzXzBBJj0jJUPKLbRV9Gd/P1keJHbPl m6KK7+m3qCRY42DKhwItZu8ndnZe/VGGCTkeZMpXN9lAmCdmR2OcFqnsb7TZoiBzZGOu zQ4rjdcByUEGcYF3Ohg2gT8ywRpJd3vE+PHkph0LFY5gCbI2qGK6QF0FkZQRgtMEBsHV cUnQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=5ZbuzWFb05kcCtlP0k1Tn6UvFIbchDgGdXuKBUi7hyI=; b=jYjxGFFcBJPGB6Pb1D0s332i0KBV2NAp0FEF0n6cgnzUbPBPv18iDNpDgOLuKjYGku bU+HvNdyGwABx0uP3JGBHVcNLDP/QHc+/kP2wQXFgn0gUkGaJmAbV+++J7Be8aZT7FtV nbfufZhkAP4bfgcC3omTXl02T4jEuIqr48JXt45Lj8c5K6wxPfVNus6S6r1DPZ84HMQa ltX2LNr7z3CJYvjBtoU/YWyA6LeFXgxNDbvXhfGOyH3ydRSdkDV7pz1QG4gL5f9SHLbv CoSBuiXP+ro4CxJO9eqnohiye2TMoWla67Kqso3djB38fUV55t4fEAvmsmQ8z/tTBt+W EfZw== X-Gm-Message-State: AOUpUlFuCw1njJmX1s+01eZJ2yQ+sVQIgp4uWxmGlE1UUwBmTw6IXt13 bzgoTUxHw3qUcZ+N7qqXblsgn1jeZc17bz5rKl5OL2/5ikg= X-Google-Smtp-Source: AAOMgpdj0KjpL8O1OcyWQUGuKKb2OJmIOQm7HIV5M+aWRelaSlbVHMLtTISalzb4DGQ1BwYDjq603UrCCIdS3kq4lVM= X-Received: by 2002:a02:a701:: with SMTP id k1-v6mr452575jam.140.1532582612438; Wed, 25 Jul 2018 22:23:32 -0700 (PDT) MIME-Version: 1.0 References: <201807252259.w6PMxhDt055842@chez.mckusick.com> In-Reply-To: <201807252259.w6PMxhDt055842@chez.mckusick.com> From: Warner Losh Date: Wed, 25 Jul 2018 23:23:21 -0600 Message-ID: Subject: Re: core dumps onto ZFS To: Kirk McKusick Cc: "Mikhail T." , fs@freebsd.org Content-Type: text/plain; charset="UTF-8" X-Content-Filtered-By: Mailman/MimeDel 2.1.27 X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.27 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 26 Jul 2018 05:23:35 -0000 On Jul 25, 2018 4:56 PM, "Kirk McKusick" wrote: Is there any chance that your filesystem was more than 90% full? Once ZFS gets past 90% full its performance drops precipitously. As it approaches completely full it locks up for minutes per write doing huge numbers of writes to its pool in an attempt to consolodate what little free space it has left into something big enough for it to use (which it sounds like is happening to you). Write amplification (the amount of extra writing described here) approaches 1 / free-space as free-space goes to zero... so 1% empty is 10x slower than 10% empty, but that is only 2x slower than 80% full. I say tends because the more free space you have, the greater the odds you have ready space to write without GC. Warner Kirk McKusick _______________________________________________ freebsd-fs@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/freebsd-fs To unsubscribe, send any mail to "freebsd-fs-unsubscribe@freebsd.org"