From owner-freebsd-stable@freebsd.org Thu Nov 26 16:32:51 2015 Return-Path: Delivered-To: freebsd-stable@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 731C4A3A5AE for ; Thu, 26 Nov 2015 16:32:51 +0000 (UTC) (envelope-from fjwcash@gmail.com) Received: from mail-ob0-x236.google.com (mail-ob0-x236.google.com [IPv6:2607:f8b0:4003:c01::236]) (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 33E3F1DA8 for ; Thu, 26 Nov 2015 16:32:51 +0000 (UTC) (envelope-from fjwcash@gmail.com) Received: by obbww6 with SMTP id ww6so66018417obb.0 for ; Thu, 26 Nov 2015 08:32:50 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; bh=+yfur5ibDvFPquBZAnRxKMGXoQAqCrvp7TZQE0/7Ees=; b=jYWA3i9x/zNi+QabRboL7gyFOc+7YwcxIAyzefo5kWkbP9oui+lla89FWp0wMw0EsL lji/iEFyjn7ouZoPo/mvlqxG/oi4PvL/MJnXeaoAJyOlTnE6M15mCT7Ai+YZM0SYiFdH //zo5OywPOf9Idq5F2vd8t+yUhXtI6ToiA8CIpmYMf95wz5PlF2ElNq04E0O3ssBdEkZ exzHrkdQgnWGRhtGiB+XM836im+OZjPpboo/YOBeiZJRnmM5w5CigUTRir1BsDy4z05i xU9vtVeB5m7XElYwfFiVrEWrK78jkXNLhDVxOaum/8PZKWa2m1AbwIbwfrZbguesLF2x Hn2Q== MIME-Version: 1.0 X-Received: by 10.182.236.101 with SMTP id ut5mr29273709obc.73.1448555570414; Thu, 26 Nov 2015 08:32:50 -0800 (PST) Received: by 10.76.80.229 with HTTP; Thu, 26 Nov 2015 08:32:50 -0800 (PST) In-Reply-To: References: <5654855F.2070502@sentex.net> <20151125081210.6ce3d9404b314fcfb31b061f@aei.mpg.de> <20151125131614.349faf4e6febeb00e401364d@aei.mpg.de> Date: Thu, 26 Nov 2015 08:32:50 -0800 Message-ID: Subject: Re: ZFS - poor performance with "large" directories From: Freddie Cash To: krad Cc: =?UTF-8?B?R2Vycml0IEvDvGhu?= , freebsd-stable Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Content-Filtered-By: Mailman/MimeDel 2.1.20 X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 26 Nov 2015 16:32:51 -0000 On Thu, Nov 26, 2015 at 2:19 AM, krad wrote: > true, but in my experience usb pen drives are variable in terms of > performance across different sticks and different areas of the same stick= . > This can complicate things a little, and is often not worth the effort. Y= ou > obviously run the ssd over usb though, and I still do on one server I run > as I haven't been able to sort the down time yet. > =E2=80=8BNowadays, USB 3.x-based sticks in USB 3.x ports should be fast eno= ugh that they'll be helpful. You won't get the full 5 Gbps from one (unless you spend as much or more than an SSD), but it will be much better than the measly 0.5 Gbps of a USB 2.x stick/port. Don't bother trying with a USB 2.x stick, or with anything plugged into a USB 2.x port. Invariably, it will just slow things down. I used to use 8 GB USB2 sticks in USB2 ports for L2ARC (with a separate one for the root filesystem). When I had 4x IDE disks in a raidz1 vdev=E2=80= =8B, they helped. When I migrated to 4x SATA1 disks in a raidz1 vdev, they helped. When I migrated to 4x SATA3 disks in dual-mirror vdevs (with root-on-ZFS), suddenly the USB stick became the bottleneck. Removing it actually made the whole system faster (better throughput, more IOps, lower latency, smoother system overall). =E2=80=8BAs always, YMMV, and test it with your own setup. :)=E2=80=8B --=20 Freddie Cash fjwcash@gmail.com