From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Message-ID: <555E8165.6070608@kernel.dk> Date: Thu, 21 May 2015 19:07:49 -0600 From: Jens Axboe MIME-Version: 1.0 Subject: Re: Urgent problem while using Fio to test random write performance References: <555D9487.3040104@cnnic.cn> <555DEA42.8020209@nellans.org> In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit To: Sitsofe Wheeler , David Nellans Cc: Nan WANG , "fio@vger.kernel.org" List-ID: On 05/21/2015 02:39 PM, Sitsofe Wheeler wrote: > On 21 May 2015 at 15:22, David Nellans wrote: >> you're randwrite to a raw partition. if you had a filesystem on that >> partition you were trying to use, then well, your data is gone/corrupted. >> without a filesystem on it, i'm not sure how you'd think that your disc >> usage has become "100%" without some xgui widgit warning you, so seems >> likely you did something you didn't mean to with regards to writing to >> /dev/sdb1 directly >> >> if you use fio on devices/partitions with a filesystem, you need to have it >> write to files or it will trash your filesystem > > It's unlikely but it wasn't mentioned which partition became 100% > full. You should also make sure that /dev/sdb1 really exists as a > block device (e.g. via using file) otherwise you'll make/fill a > standard file called /dev/sdb1 . That's true, though on modern systems that will fail since /dev is mounted on devtmpfs which doesn't support O_DIRECT. In general, allow_file_create=0 can be used to turn off file creation if you expect to run on block devices. This can avoid problems like this. -- Jens Axboe