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Bottomley" , "Martin K. Petersen" , Jonathan Corbet , Linux Kernel Mailing List , linux-scsi@vger.kernel.org, linux-doc@vger.kernel.org Subject: Re: [PATCH] scsi: sd: stop SSD (non-rotational) disks before reboot Message-ID: <20200705213125.GC8285@khazad-dum.debian.net> References: <499138c8-b6d5-ef4a-2780-4f750ed337d3@0882a8b5-c6c3-11e9-b005-00805fc181fe> <20200618072138.GA11778@infradead.org> <9877e7de-d573-694b-2b75-95192756684b@0882a8b5-c6c3-11e9-b005-00805fc181fe> <20200618134904.GA26650@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200618134904.GA26650@infradead.org> X-GPG-Fingerprint1: 4096R/0x0BD9E81139CB4807: C467 A717 507B BAFE D3C1 6092 0BD9 E811 39CB 4807 User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org On Thu, 18 Jun 2020, Christoph Hellwig wrote: > > For SSDs, I don't think an extra stop should ever be an issue. > > Extra shutdowns will usually cause additional P/E cycles. I am not so sure. We're talking about enforcing clean shutdowns here (from the SSD PoV). A system reboot takes enough time that the SSD is likely to do about the same amount of P cycles commiting to FLASH any important data that it would trigger by a shutdown sequence, simply because it should not keep important data in RAM for too long. By extension, it would not increase E cycles either. OTOH, unclean shutdowns *always* cause extra P/E, and that's if you're lucky enough for it to not cause anything much worse. -- Henrique Holschuh