paolozXXII 2 Posted February 23 Posted February 23 Hi, I have a Synology 920+ with 1x 256Gb SSD Cache (yes, read-only). I was wondering if the load of the entire movie can be "forced" in the SSD cache, thus avoiding or mitigating the lawnmower noise of the disks for the entire duration of a movie... P.S. When Movie station was deprecated, I tried Plex, Emby and the other one suggested by Synology. After two days of tests I bought the Premiere License right away as I was really impressed by the great job you've done! Thanks a lot! 1
Luke 39654 Posted February 23 Posted February 23 Hi, there is no option in Emby for this, although in my testing I have found that the SSD cache drive on Synology helps the performance of the entire NAS, including Emby Server.
paolozXXII 2 Posted February 24 Author Posted February 24 Thanks Luke. As far as I red, the improvement is mainly on home page rendering... I still think a good idea though: a 10-15 GB movie can be cached in few minutes and then "enjoy the silence". It would also benefit concurrent accesses... Cheers Paolo 1
Carlo 4547 Posted February 25 Posted February 25 The algorithms used by Synology for caching leaves a lot to be desired IMHO. For example, with a single drive you can't cache writes. With 2 drives set in RAID 0 you get 2x cache speed as well as deferred write caching which helps a lot. In theory you really don't want to fully copy the complete media file to the cache but instead reduce IO as much as possible based on the current workload of the main drives, the drives latency of specific ops and of course the hit rate of the cache. A cache should not eject/delete existing data, especially if it has a good hit rate without a reason. If a media file is being loaded from HDD and there are no latency issues or read/write queues building up there is nothing gained involving the cache at all since it would just be additional IO. On the other hand, if latency and/or queues are building up due to drive thrashing where heads are jumping from outside to inside the platters then over-reading inside platters (normally) to cache them makes sense as it reduces the access time of the disks as less head movement is needed. Disk caching like this is normally built into the kernel OS and highly tunable, but on Synology it's handled by DiskStation Manager (DSM).
paolozXXII 2 Posted February 26 Author Posted February 26 Carlo, I do agree on your explanation, but there's no doubt that loading a 5 Gb movie into a 250 GB cache will be more energy-efficient than loading chunks every now and then, as I believe that in any case they'll be loaded into the SSD cache anyway... Yet, back to Synology for this, as long as there are specific APIs that can be be exploited/used by Emby Server... Cheers, and thanks for your reply. Paolo
Carlo 4547 Posted February 26 Posted February 26 What does disk station show for the cache hit rate? How full is the cache drive?
paolozXXII 2 Posted February 27 Author Posted February 27 Hi, avg in a month is 50% Reusable is 180Gb on 236 Paolo
paolozXXII 2 Posted March 2 Author Posted March 2 I hope so, I do not want to have a write cache, that's why I chose a single nvme, the recommendation after 3 weeks analysis was about 120GB... I had a 256 spare so... Back to the RFE, I do think the only way is dig in to the Synology's API and force-load the entire movie... Thanks you all for your support.
Carlo 4547 Posted March 3 Posted March 3 I'd reconsider the write cache as it can make a difference on a lot of short term writes such as transcoding and remixing.
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