Hi David The io performance decreases when sync io happens. It's expected. How about the performance without sync io? And what's your kernel version? I read other emails in this thread too. Your sync speed also decreases in three days. I can't understand this. What's the io environment there? It's better to describe more about the situation too. Regards Xiao On Sat, Mar 8, 2025 at 2:36 AM David Hajes <d.hajes29a@xxxxx> wrote: > > Hi guys, > > I have issues with RAID5 running on post-2020 14TB drives. > > I am getting max writting speeds of 220MBs. > > If I understood properly docs, RAID5 with three drives should have 2x write/read speeds. > > Single drive tests running 190-220MBs, no issues in SMART reports. > > RAID5 with 4 drives...same speed. > > RAID10 should have 2x write, 4x read...still running 220MBs max as RAID5 > > I have played with chunk size...default 512k-2MBs...no difference > > "Read-ahead" set for md0 virtual disk > > NCQ disabled - set 1 for all physical drives > > I have basically tried every suggestion on famous ArchWiki. > > I have tried SAS2 HBA...same results. > > Initial resync drops to 130MBs > > Debian 12 running on SuperMicro 10 series MB. 32GB RAM, cpu max 30% load during tests/real-life copy. > > Is it possible this weird issue is linked to HDD timeout described there >>> https://archive.kernel.org/oldwiki/raid.wiki.kernel.org/index.php/Timeout_Mismatch.html > > Any suggestion, please? > > Array should be doing 260-560MBs with ease > > Regards > > Hajes >
