> -----Original Message----- > From: linux-btrfs-ow...@vger.kernel.org <linux-btrfs- > ow...@vger.kernel.org> On Behalf Of Tomasz Chmielewski > Sent: Saturday, 5 January 2019 12:25 AM > To: Btrfs BTRFS <linux-btrfs@vger.kernel.org> > Subject: dedicated metadata drives? > > According to btrfs wiki, some patches have been submitted to support > metadata on different devices than data (i.e. metadata on SSD, data on > HDD): > > > https://btrfs.wiki.kernel.org/index.php/Project_ideas#Dedicated_metadata > _drives > > Dedicated metadata drives > > Not claimed — submitted — Not in kernel yet > > We're able to split data and metadata IO very easily. Metadata tends to be > dominated by seeks and for many applications it makes sense to put the > metadata onto faster SSDs. > > > > > This article (almost 2.5 years old) claims one company is already using either > these patches or something similar: > > https://lwn.net/Articles/698090/ > > August 24, 2016 > > To combat that, he has a set of patches to automatically put the Btrfs > metadata on SSDs. The block layer provides information on whether the > storage is rotational; for now, his patch assumes that if > it is not rotational then it is fast. The patch has made a huge > difference in > the latencies and requires less flash storage (e.g. 450GB for 40TB filesystem) > for Facebook's file workload that > consists of a wide variety of file sizes. > > > > Do these patches exist anywhere? I couldn't find them in the list archive.
I managed to find this suggestion about how it could be done: https://patchwork.kernel.org/patch/9556973/ I would love to use this feature as well. My current setup uses btrfs on lvm with caching enabled, but I would prefer a simpler setup. Paul.
