On Fri, Oct 10, 2025 at 08:55:38PM +0200, Franco Martelli wrote:
Is it safe and the right thing to do increase the value of: "stripe_cache_size"? The default value is:~# cat /sys/block/md0/md/stripe_cache_size 256
no
or play with "speed_limit_max" value, the default is: ~# cat /proc/sys/dev/raid/speed_limit_max 200000
yes, increase this. I usually use a value of 10000000 (effectively "no limit"). So why does this tunable exist? The general idea is to make it possible to ensure that a RAID resync doesn't starve out other use of the array, by setting a lower maximum bandwidth. The value of 200MByte/s was chosen 20 years ago as a number well in excess of drive speeds...but drives have gotten a lot faster while the default hasn't changed. A SATA SSD can hit about 550MByte/s on a RAID resync, and even a good modern hard drive can get over 250MByte/s. NVMe storage can easily get over a GByte/s, once the speed limit is raised.