March 21, 20188 yr I find myself needing more than the 512GB SSD in space but dont want to use a cache pool to add more. I can get a 2TB SSHD cheap and wanted to see what others thought about SSHD vs SSD for cache drives.
March 22, 20188 yr SSHDs are a bit crap. They only just about work for booting Windows. I don't think their algorithms would know what to do with an unRAID cache drive. They're cheap for a reason. Just go for a decent HDD like a WD Black or Gold, or any 7200rpm Seagate. I quite like using a 2.5" 7200rpm drive for a cache on my backup boxes, they use very little power and are quick enough. I tend to use HGST 2.5" drives, and had no issues with them.
March 22, 20188 yr 5 hours ago, HellDiverUK said: I don't think their algorithms would know what to do with an unRAID cache drive. They try to keep an LRU list of accesses and if some of the blocks in the LRU gets enough number of reads (but not writes) the HDD will then copy these blocks to the tiny flash cache. This does not work with how a write cache is used in unRAID. A SSHD could optimize some block reads for a VM stored on the disk but will not be able to work any better than a normal HDD for handling copying of data to the array.
March 22, 20188 yr Author 42 minutes ago, pwm said: They try to keep an LRU list of accesses and if some of the blocks in the LRU gets enough number of reads (but not writes) the HDD will then copy these blocks to the tiny flash cache. This does not work with how a write cache is used in unRAID. A SSHD could optimize some block reads for a VM stored on the disk but will not be able to work any better than a normal HDD for handling copying of data to the array. Thank you all for your responses and especially thank you to PWM for this reply. This is the type of info I was looking for. I have some WD Blacks available and will try that option out as HellDriverUK suggested.
March 22, 20188 yr They work great for gaming drives, where the games you frequently play fit in the cache. But I think that's about it.
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