From owner-freebsd-questions@freebsd.org Wed Dec 20 14:13:38 2017 Return-Path: Delivered-To: freebsd-questions@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 1C7BEE8B501 for ; Wed, 20 Dec 2017 14:13:38 +0000 (UTC) (envelope-from rwmaillists@googlemail.com) Received: from mail-wm0-x22a.google.com (mail-wm0-x22a.google.com [IPv6:2a00:1450:400c:c09::22a]) (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 9CC846EF47 for ; Wed, 20 Dec 2017 14:13:37 +0000 (UTC) (envelope-from rwmaillists@googlemail.com) Received: by mail-wm0-x22a.google.com with SMTP id g75so10221848wme.0 for ; Wed, 20 Dec 2017 06:13:37 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:subject:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=MUz7OM1qcfgk0R19wqQT3/yiorLr5dGr6nelHTQ8Puc=; b=bfsPjuTItAdSliSRgUtE8901tfbkXFayYPcg8tccogxgBjV70NDiHs/Bj8dOXqDsQK qzC00GSldlYdl+bg6bFD/0R6kHCqI82gTHNMGNmSTF42KSs6Ny10nTsyuzzeVtBwlSTu zl9VoGlQHydrrj6ATKpRt4ELiv60drMRwwoRxq7yoL/XCsK+TPeWPN7py8YvyFIycYz/ ab57ngGgNMYADWg6NWHPAGpHLsuqkVX0A2fZMaDZ9JmvRNso7zV1m2y3Mly1aca1+DFp fm7RHpGFf17lfinPluqyHjkOaBRMqqhd37knNFOqMD315MwF7tqo41FNSbKP9gO2nhkK FJPQ== X-Gm-Message-State: AKGB3mLhCnCPQyXKaPP5XgI/6vm73iqwTl6d4lWknlruDaaw6Ve8DXUZ Nhd4EYRX2tvfD3AZ1dKEj+Ax2Q== X-Google-Smtp-Source: ACJfBotTdzKVzMK/YlpOPefcg1aMO31LoRnFB9mCOEFmhSHakVTifP6/dvi3FTt3nt1VAUPgO3pHkQ== X-Received: by 10.80.220.132 with SMTP id r4mr534676edk.180.1513779215673; Wed, 20 Dec 2017 06:13:35 -0800 (PST) Received: from gumby.homeunix.com ([81.17.24.158]) by smtp.gmail.com with ESMTPSA id a38sm14175067edf.3.2017.12.20.06.13.34 for (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 20 Dec 2017 06:13:34 -0800 (PST) Date: Wed, 20 Dec 2017 14:13:32 +0000 From: RW To: freebsd-questions@freebsd.org Subject: Re: hd firecuda Message-ID: <20171220141332.3fa53ab5@gumby.homeunix.com> In-Reply-To: <20171220105300.1497c3a9.freebsd.ed.lists@sumeritec.com> References: <1513447749.62024.1.camel@yandex.com> <20171217112428.150d8041.freebsd.ed.lists@sumeritec.com> <20171217111319.6a1af590@gumby.homeunix.com> <20171217194753.3ab59e6d.freebsd.ed.lists@sumeritec.com> <20171217150007.642efc20@gumby.homeunix.com> <20171218085219.2fec7c3b.freebsd.ed.lists@sumeritec.com> <20171218162625.5bcc543e@gumby.homeunix.com> <20171219081418.5672730b.freebsd.ed.lists@sumeritec.com> <20171219144606.0217ee55@gumby.homeunix.com> <20171220105300.1497c3a9.freebsd.ed.lists@sumeritec.com> X-Mailer: Claws Mail 3.15.1 (GTK+ 2.24.31; amd64-portbld-freebsd11.1) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.25 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 20 Dec 2017 14:13:38 -0000 On Wed, 20 Dec 2017 10:53:00 +0800 Erich Dollansky wrote: > Hi, > > On Tue, 19 Dec 2017 14:46:06 +0000 > RW via freebsd-questions wrote: . On long writes, this space will also be filled. > > > > It's unlikely that it would fall back to discarding useful cache in > > the SSD *after* filling the larger non-shingled area of the drive. > > If that bit of extra buffering made a useful difference they'd just > > increase the size of the non-shingled area. > > how to increase the non-shingled area without shrinking the drive's > available size? They'd design it with the right size in the first place using their experience with ordinary shingled drives. > > IMO what you are seeing is consistent with selective read caching > > plus write caching into the non-shingled area. > > How do you explain then the deep breath? What do I call a deep breath? > An access which takes more than a minute. It only happens when huge > amounts of data is written to the drive like updating sources and > ports tree and then starting to compile them. Any explanation you have involving buffering writes through flash also fits buffering through the non-shingled area.