From nobody Wed Jan 28 16:00:36 2026 X-Original-To: freebsd-questions@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 4f1Rnm3jB2z6QHhg for ; Wed, 28 Jan 2026 16:00:44 +0000 (UTC) (envelope-from guru@unixarea.de) Received: from ms-10.1blu.de (ms-10.1blu.de [178.254.4.101]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (prime256v1) server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 4f1Rng2zyVz3Kw1 for ; Wed, 28 Jan 2026 16:00:39 +0000 (UTC) (envelope-from guru@unixarea.de) Authentication-Results: mx1.freebsd.org; dkim=pass header.d=unixarea.de header.s=blu3434000 header.b=Cr4P9fvX; dmarc=none; spf=pass (mx1.freebsd.org: domain of guru@unixarea.de designates 178.254.4.101 as permitted sender) smtp.mailfrom=guru@unixarea.de DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=unixarea.de ; s=blu3434000; h=Content-Transfer-Encoding:Content-Type:MIME-Version: Reply-To:Message-ID:Subject:To:From:Date:Sender:Cc:Content-ID: Content-Description:In-Reply-To:References; bh=4dfijoCdjI5EUxKhDiOx5AWe+wHlCMOYMfWhZq4Lw/E=; b=Cr4P9fvXV8FsZlmZEb/SvL5fWW 6UE30u16OXuG4osiQiHR9LCTx6cgkN8Al/Za4ZriDvDVib5nyRqHL50nhPWY5yQOiiVSB9L7TYh3Q jZoWzTEJgBd2/etx26jcjC4ohiUNw75jxqa06zYKHQ9WaTUJ6ogNIrlPBSgSglMXYvMXLx+3+DI4t LXS6NzxiEOKSGtn1jfwb58olffxiXeEE1FFUqY7sQPD04vY+Ymj7elTX9H2tDMTlM2l5H2HFYn1Rt +gmvwUq0i+a04PXlcMKi8q0ma25Mu5ORquRZsHYqy3TSKNE5TpBCc2mM7jpCTwrGmhex3zzSs5vmk g5XLuAFw==; Received: from [62.216.207.59] (helo=localhost.unixarea.de) by ms-10.1blu.de with esmtpsa (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.95) (envelope-from ) id 1vl7y9-00Fc3m-6x for freebsd-questions@freebsd.org; Wed, 28 Jan 2026 17:00:37 +0100 Received: from localhost.my.domain (c720-1400094 [127.0.0.1]) by localhost.unixarea.de (8.17.1/8.14.9) with ESMTP id 60SG0ag3004210 for ; Wed, 28 Jan 2026 17:00:36 +0100 (CET) (envelope-from guru@unixarea.de) Received: (from guru@localhost) by localhost.my.domain (8.17.1/8.14.9/Submit) id 60SG0agd004209 for freebsd-questions@freebsd.org; Wed, 28 Jan 2026 17:00:36 +0100 (CET) (envelope-from guru@unixarea.de) X-Authentication-Warning: localhost.my.domain: guru set sender to guru@unixarea.de using -f Date: Wed, 28 Jan 2026 17:00:36 +0100 From: Matthias Apitz To: freebsd-questions@freebsd.org Subject: external USB disk: 400MB/s transfer, but get only 40MB/s Message-ID: Reply-To: Matthias Apitz Mail-Followup-To: freebsd-questions@freebsd.org List-Id: User questions List-Archive: https://lists.freebsd.org/archives/freebsd-questions List-Help: List-Post: List-Subscribe: List-Unsubscribe: X-BeenThere: freebsd-questions@freebsd.org Sender: owner-freebsd-questions@FreeBSD.org MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit X-Operating-System: FreeBSD 14.0-CURRENT r1400094 (amd64) X-message-flag: Mails in HTML will not be read! Please, only plain text. X-Con-Id: 51246 X-Con-U: 0-guru X-Originating-IP: 62.216.207.59 X-Spamd-Bar: -- X-Spamd-Result: default: False [-3.00 / 15.00]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_MEDIUM(-1.00)[-1.000]; NEURAL_HAM_SHORT(-1.00)[-0.997]; MID_RHS_NOT_FQDN(0.50)[]; R_DKIM_ALLOW(-0.20)[unixarea.de:s=blu3434000]; R_SPF_ALLOW(-0.20)[+ip4:178.254.4.101]; MIME_GOOD(-0.10)[text/plain]; RCVD_TLS_LAST(0.00)[]; RCVD_COUNT_THREE(0.00)[3]; HAS_XAW(0.00)[]; SUSPICIOUS_AUTH_ORIGIN(0.00)[]; MIME_TRACE(0.00)[0:+]; DMARC_NA(0.00)[unixarea.de]; RCPT_COUNT_ONE(0.00)[1]; ARC_NA(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; MISSING_XM_UA(0.00)[]; HAS_REPLYTO(0.00)[guru@unixarea.de]; TO_DN_NONE(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; DKIM_TRACE(0.00)[unixarea.de:+]; PREVIOUSLY_DELIVERED(0.00)[freebsd-questions@freebsd.org]; MLMMJ_DEST(0.00)[freebsd-questions@freebsd.org]; HAS_XOIP(0.00)[]; ASN(0.00)[asn:42730, ipnet:178.254.0.0/19, country:DE]; RCVD_VIA_SMTP_AUTH(0.00)[]; REPLYTO_EQ_FROM(0.00)[] X-Rspamd-Queue-Id: 4f1Rng2zyVz3Kw1 Hello, I did tests on two laptops (ASUS and C720) with different USB disks, and writing with # dd if=file of=/mnt/file bs=8m a big file of many GBytes, see below. The disk was always announced in /var/log/messages as a 400.000MB/s transfers devices by the driver, but the measured transfer was only between 40MB/s and 50MB/s. The file system on the USB disks was NTFS. Why is this? matthias Jan 25 10:57:41 ASUS-150 kernel: da0: Fixed Direct Access SPC-4 SCSI device Jan 25 10:57:41 ASUS-150 kernel: da0: 400.000MB/s transfers 82594649636 bytes transferred in 2005.078575 secs (41192725 bytes/sec) Jan 25 11:57:26 ASUS-150 kernel: da0: Fixed Direct Access SPC-4 SCSI device Jan 25 11:57:26 ASUS-150 kernel: da0: 400.000MB/s transfers 82594649636 bytes transferred in 1492.881431 secs (55325659 bytes/sec) Jan 25 13:08:13 c720-1400094 kernel: da0: Fixed Direct Access SPC-4 SCSI device Jan 25 13:08:13 c720-1400094 kernel: da0: 400.000MB/s transfers 46271915961 bytes transferred in 1081.647154 secs (42779122 bytes/sec) -- Matthias Apitz, ✉ guru@unixarea.de, http://www.unixarea.de/ +49-176-38902045 Public GnuPG key: http://www.unixarea.de/key.pub