FlyingTexan Posted June 19, 2021 Share Posted June 19, 2021 So I've just added a 2TB SSD and 2x8TB HDD. The HDD are now formatted and fine. My question is what's going on with the SSD? I've just setup Radarr and Sonarr so hitting it hard for now to get my database setup. The SSDs show correctly the 4TB however they appear to only have 3TB usable. What do I need to do to get my other 1TB back? On another note is there a means to have the SSD cache start unloading files to the HDD array immediately? With a 100MB or so download as well as the extraction of files the SSDs should still have the bandwidth to start sending data to the array. This would really buy a lot of time. I can select for it to start balancing (not exactly sure what this does) but wanted it to be automatic. When you select to balance does it take 100% of the files on the SSD cache and move them to the array? Quote Link to comment
JonathanM Posted June 19, 2021 Share Posted June 19, 2021 Pools default to RAID1, which would mean you have 2TB usable space with full redundancy using the drives you have listed. You would need to change the desired RAID level and rebalance if that is not what you want. I suspect when you added the 2TB it did not get properly balanced into the pool. Each share has a setting to determine where files will initially be placed and whether the mover will change their location. Your screenshot shows mover to already be running, so shares set to cache : yes will be moving from the cache pool to the array. Quote Link to comment
FlyingTexan Posted June 19, 2021 Author Share Posted June 19, 2021 9 minutes ago, jonathanm said: Pools default to RAID1, which would mean you have 2TB usable space with full redundancy using the drives you have listed. You would need to change the desired RAID level and rebalance if that is not what you want. I suspect when you added the 2TB it did not get properly balanced into the pool. Each share has a setting to determine where files will initially be placed and whether the mover will change their location. Your screenshot shows mover to already be running, so shares set to cache : yes will be moving from the cache pool to the array. My pool has been operating in raid 0 prior to adding the drive. I'm seeing 3TB usable so even if it defaulted back to raid 1 wouldn't I only see 2TB? Thank you for the quick response! Quote Link to comment
trurl Posted June 19, 2021 Share Posted June 19, 2021 It is impossible to move from cache to array as fast as you can write to cache, so if you intend to write more than cache can hold, don't cache. Quote Link to comment
FlyingTexan Posted June 19, 2021 Author Share Posted June 19, 2021 1 minute ago, trurl said: It is impossible to move from cache to array as fast as you can write to cache, so if you intend to write more than cache can hold, don't cache. Yes I understand. However if the cache only syncs one a day then at most the system could download 4TB before slowing down. With the cache able to handle the bandwidth I was curious if it could sync as soon as it starts receiving data. This could greatly extend the time the cache is usable until full. Quote Link to comment
trurl Posted June 19, 2021 Share Posted June 19, 2021 2 minutes ago, FlyingTexan said: raid 0 prior to adding the drive. I'm seeing 3TB 3TB is the correct answer for your configuration: https://carfax.org.uk/btrfs-usage/ You would need to use Single mode to get full capacity from different sized disks: Quote Link to comment
trurl Posted June 19, 2021 Share Posted June 19, 2021 You can change the Mover schedule, but Mover is intended for idle time. Just write directly to the array and it will already be protected by parity. Quote Link to comment
itimpi Posted June 19, 2021 Share Posted June 19, 2021 4 minutes ago, trurl said: 3TB is the correct answer for your configuration: https://carfax.org.uk/btrfs-usage/ You would need to use Single mode to get full capacity from different sized disks: I would have thought the correct answer is 2TB for RAID1 profile, and the 3TB is the known issue of BTRFS reporting incorrectly with an odd number of drives? Quote Link to comment
JonathanM Posted June 19, 2021 Share Posted June 19, 2021 1 minute ago, itimpi said: I would have thought the correct answer is 2TB for RAID1 profile, and the 3TB is the known issue of BTRFS reporting incorrectly with an odd number of drives? 3TB is RAID0, where each chunk of data is striped across all devices for speed. I forgot that tidbit when I initially replied. The odd number of drives thing makes BTRFS RAID levels rather unpredictable with usual logic, which is probably why free space calculation is hard in that config. Quote Link to comment
JorgeB Posted June 20, 2021 Share Posted June 20, 2021 IIRC raid0 with an odd number of equal size drives reports space correctly, problem here is likely the different size drives, but the free space will be less wrong as the pool gets filled, and you can use the full space, which as mentioned is 3TB in this case. Quote Link to comment
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