Stupid me forgot half of what I wanted to write: On 11.02.2017 16:15, Thorsten Leemhuis wrote: > Lo! You afaics want to configure the hdd as "writemostly". Google for > the term in combination with "linux" or "mdadm". It'll lead to pages > like this: > http://tansi.info/hybrid/ > http://hatim.eu/2014/05/25/leveraging-ssd-ephemeral-disks-in-ec2-part-2/ I forgot to write here: Some of those links will show that others (just like you and me) found that writemostly doesn't work that well. I had similar results and stopped using it. Iirc upstream added it as a quick hack that in the end didn't work that well, so it hasn't a high priority there and it's a known problem. Got that impression after reading some mails in the archives when I was looking into writemostly a year or two ago, but can't find those right now :-/ CU, knurd > P.S.: I considered not answering the question, because it afaics and > imho is off topic here (hence a answer only encourages people to send > more questions like this), as the question is not specific to Fedora in > any way. But this list is for "*Fedora kernel development*. This list is > used for discussion of changes to the Fedora kernel that aren't > necessarily relevant to the upstream kernel list. […]" (quote from > https://lists.fedoraproject.org/admin/lists/kernel.lists.fedoraproject.org/ > ) Hence I think you should send questions like that to a more general > Linux kernel mailing list in the future. But as I said: That just my option. > > On 11.02.2017 15:16, Reindl Harald wrote: >> /dev/sda: Samsung SSD 850 EVO 2TB >> /dev/sdb: Samsung SSD 850 EVO 2TB >> /dev/sdc: ST2000DX002-2DV164 >> /dev/sdd: ST2000DX002-2DV164 >> >> normally i would expect that for heavy read-IO the two HDD drives would >> sleep and the two SSD working more or less like a RAID0 but as example >> running a btrfs-srub within a virtual machine on a 1.5 TB vdisk you can >> hear the rotating disks clearly and there are also unexpected lags while >> a disk IO auf around 700 MB/sec shows that it's basicly working >> >> pretty sure the lags are coming because read-access is also spread to >> HDD - why is that? >> >> /dev/md2: >> Version : 1.1 >> Creation Time : Wed Jun 8 13:10:56 2011 >> Raid Level : raid10 >> Array Size : 3875222528 (3695.70 GiB 3968.23 GB) >> Used Dev Size : 1937611264 (1847.85 GiB 1984.11 GB) >> Raid Devices : 4 >> Total Devices : 4 >> Persistence : Superblock is persistent >> >> Intent Bitmap : Internal >> >> Update Time : Sat Feb 11 15:10:31 2017 >> State : active >> Active Devices : 4 >> Working Devices : 4 >> Failed Devices : 0 >> Spare Devices : 0 >> >> Layout : near=2 >> Chunk Size : 512K >> >> Name : localhost.localdomain:2 (local to host >> localhost.localdomain) >> UUID : ea253255:cb915401:f32794ad:ce0fe396 >> Events : 1818029 >> >> Number Major Minor RaidDevice State >> 4 8 35 0 active sync set-A writemostly >> /dev/sdc3 >> 5 8 19 1 active sync set-B /dev/sdb3 >> 7 8 51 2 active sync set-A writemostly >> /dev/sdd3 >> 6 8 3 3 active sync set-B /dev/sda3 >> _______________________________________________ >> kernel mailing list -- kernel@xxxxxxxxxxxxxxxxxxxxxxx >> To unsubscribe send an email to kernel-leave@xxxxxxxxxxxxxxxxxxxxxxx >> _______________________________________________ kernel mailing list -- kernel@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe send an email to kernel-leave@xxxxxxxxxxxxxxxxxxxxxxx
