From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from lucy.dinwoodie.org (77.116.2.81.in-addr.arpa [81.2.116.77]) by sourceware.org (Postfix) with ESMTPS id B33953858D39 for ; Mon, 31 Jan 2022 21:36:16 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org B33953858D39 Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=dinwoodie.org Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=dinwoodie.org Received: from adam by lucy.dinwoodie.org with local (Exim 4.94.2) (envelope-from ) id 1nEeLP-00076O-3U for cygwin@cygwin.com; Mon, 31 Jan 2022 21:36:15 +0000 Date: Mon, 31 Jan 2022 21:36:15 +0000 From: Adam Dinwoodie To: cygwin@cygwin.com Subject: Re: Renaming (with 'mv') very large files is SLOW Message-ID: <20220131213615.l3bvoyacl3jcvls2@lucy.dinwoodie.org> References: <25079.63376.349893.86395@consult.pretender> <25079.64935.73349.331715@consult.pretender> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <25079.64935.73349.331715@consult.pretender> X-Spam-Status: No, score=-0.9 required=5.0 tests=BAYES_00, KAM_DMARC_STATUS, PDS_RDNS_DYNAMIC_FP, RDNS_DYNAMIC, SPF_HELO_PASS, SPF_PASS, TXREP, T_SCC_BODY_TEXT_LINE autolearn=no autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on server2.sourceware.org X-BeenThere: cygwin@cygwin.com X-Mailman-Version: 2.1.29 Precedence: list List-Id: General Cygwin discussions and problem reports List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 31 Jan 2022 21:36:18 -0000 On Mon, Jan 31, 2022 at 10:17:59AM -0500, cygwin@kosowsky.org wrote: > Eliot Moss wrote at about 09:59:17 -0500 on Monday, January 31, 2022: > > On 1/31/2022 9:52 AM, cygwin@kosowsky.org wrote: > > > I tried renaming some very large files (20-40 GB) using: > > > mv > > > without changing the directory of course. > > > > > > The process took about 10-20 minutes with Task Manager showing disk > > > activity of 100+ MB/s. > > > > > > Is there something about such large 'renaming' that actually results > > > in the file being really moved (aka copied) rather than just renamed? > > > > The two places are probably on different volumes (loosely, different disks). > > That requires a physical move, even under Linux. > > No my point is I am just *renaming*, not physically moving the file!! > i.e., I am not changing the directory location of the file, let alone > the volume/disk location. > (I am well aware that 'mv' does a copy when changing volumes/disks). > > I literally am typing something like: > mv foo bar > > In Linux, that just edits the file system table & inode... > > UPDATE... > I just tried a second 'mv' and it was near instantaneous. > (and similarly with subsequent renaming of the same file) > So perhaps not a 'Cygwin' thing but something going on within Windows. > > Could it be that the first 'mv' triggered an anti-virus read of the file since > perhaps it detects it as a new/changed file? > > But if so, would 'mv' (under Task Manager) be showing the 100+ MB/s disk activity? That definitely seems plausible; there's a reason a significant number of the applications that are known to interfere with Cygwin operation (see [0]) are antivirus applications. But what would trigger your antivirus to want to scan a file, and how much work is required to do that, is something you'll need to take up with your antivirus vendor, I'm afraid. [0]: https://cygwin.com/faq/faq.html#faq.using.bloda