Am 08.06.19 um 07:15 schrieb Sarah Newman: > On 6/7/19 4:22 AM, Andy Smith wrote: >> On Sat, Jun 01, 2019 at 05:39:25AM +0000, Andy Smith wrote: >>> On Fri, May 31, 2019 at 09:43:35AM +0800, Guoqing Jiang wrote: >>>> There are some optimizations in raid1's read_balance for ssd, unfortunately, >>>> raid10 didn't have similar code. >> >> […] >> >>> Is it just that no one has tried to apply the same optimizations to >>> RAID-10, or is it technically difficult/impossible to do this in >>> RAID-10? >> >> Guoqing sent me a patch off-list that implements these same device >> selection optimizations to RAID-10, and it seems to work. RAID-10 >> random read performance in this setup is now the same as RAID-1 >> (both very near to fastest device) and sequential read is even >> better than RAID-1. >> >> http://strugglers.net/~andy/blog/2019/06/06/linux-raid-10-fixed-on-imbalanced-devices/ > > We've been seriously considering switching from raid10 to lvm stripes across raid1 for a different reason. > > Crucial/Micron SSDs, even the enterprise ones, do not always finish smart tests under some read loads. With RAID1 we could set them temporarily to > write-mostly so that they can finish their smart tests and vendor tests. It would be really nice if with RAID10 we could also set drives to write-mostly. funny, 2 years ago as i came up with that after finding out the hard way that my hybrid RAID10 don't work as expected nobody cared at all except one guy which after some negative respone statet that he isn't a kernel developer at all.... obiously that linux RAID10 is not a RAID10 as anywhere else now comes with it's drawbaks and the optimizatiojs from the past for rotating media becone a problem these days
