Also check congested_write_threshold_us, if the SSD is "congested" it bypasses it to speedup writes. Killian De Volder On 30-12-16 09:38, Jure Erznožnik wrote: > I have a large array sitting in my server containing a bit of data > that is used ofter and a lot of data that is used rarely. > My goal is to make the platters spin up as rarely as possible while > bcache handles most of the requests to the array. > > I have set the disks spin-down time to 15 minutes so that during > high-activity periods they don't cycle power states too much. > > I have set bcache parameters such: > cache_mode - writeback > readahead - 0 > sequential_cutoff - 0 > writeback_delay - 3600 (one hour) > writeback_percent - 40 (won't go higher) > > I was hoping that this would make bcache cache everything leaving the > array practically untouched for an hour. However, stats_hour/bypassed > still shows megabytes of bypassed data and a cache_hit ratio of ~50% > even when I'm working ONLY with the frequently accessed data portion > (some 20% of total cache capacity). Also tiny writes are being made to > the array despite writeback_delay not expiring. > > What other parameter am I forgetting to achieve what I want? > > Thanks, > Jure > -- > To unsubscribe from this list: send the line "unsubscribe linux-bcache" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe linux-bcache" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
