Am 11.02.2017 um 16:15 schrieb Thorsten Leemhuis:
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 really have no ieda what you try to tell me
please look again at the subject and the mdadm output because *they are*
set "writemostly" but there is way too much read-io on the HDD's
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
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