From mboxrd@z Thu Jan 1 00:00:00 1970 From: sim@linux.vnet.ibm.com (Narasimhan V) Date: Mon, 31 Jul 2017 20:11:59 +0530 Subject: [PATCH] nvme: avoid connecting to the same subsystem from the same path gain. In-Reply-To: <31fc10fb-386a-c430-4ca6-1a48e6b356d0@huawei.com> References: <1493040417-15680-1-git-send-email-guanjunxiong@huawei.com> <20170424145842.GA32128@infradead.org> <4e371196-36af-a389-a1a2-bdac1bb70e21@huawei.com> <20170427064041.GB28074@infradead.org> <31fc10fb-386a-c430-4ca6-1a48e6b356d0@huawei.com> Message-ID: On 2017-04-27 12:46, Guan Junxiong wrote: > On 2017/4/27 14:40, Christoph Hellwig wrote: >> On Tue, Apr 25, 2017@09:20:00AM +0800, Guan Junxiong wrote: >>> Hi ,Christoph: >>> What's the benefits of this feature? If we execute the following >>> cmd >>> 10 times, it will generate 10 character and at least 20 block >>> devices. >> >> The number of block devices will depend on the number of namespaces >> configured, but yes, this is expected. The NVMe architecture allows >> for multiple connections from a given host to a subsystem. >> >> . >> > Hi, Christoph,Thanks for your reply! > > Currently, the number of block devices will depend on both the number > of > namespaces configured in a subsystem and the number of connections > created by > connect command. > > In addition , I still have the suggestion: > Can this feature or problematic behavior be adjusted to prevent > generating > another block devices when a new connection is created from a given > host to > a subsystem via the same patho< Maybe a character device (controller) > or > block device (namespaces) can represent more connections given the same > path. > > Looking forward for you response. Thanks. Hellwig, I think this is more of a confusing/problematic behaviour than a feature, as stated. We might connect to same subsystem again, and see a different nvme subsystem, block devices. Tools like fdisk will discover duplicate block devices as different ones. So, we might think it is a different subsystem. And thus, might have data corruption issues. Looking forward for your clarification in such scenarios, and probably your take on this being feature vs issue. -- Regards Narasimhan V