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The idea you want tiering... at home.. just seems so unlikely to save you any serious money, or gain you significant performance. "tiering" in the traditional

The idea you want tiering... at home.. just seems so unlikely to save you any serious money, or gain you significant performance. "tiering" in the traditional sense isn't even popular in the DC with things like Vast, Pure, etc all doing well. Is there any reason you don't know the data set that is generally cold? The vast majority of home users basically have data that is trivially super cold that needs reasonable read performance - this is just HDDs. Then have a second mount point with things that you need greater performance, and have that be just SSDs.

the8472 3y ago
Having frequently used file metadata on SSDs while the cold parts are on HDDs would be noticeable even at home; the moment you start browsing the directory tree.
- seized 3y ago
  ZFS on Linux has exactly this, you can specify specific devices to hold metadata. Caveats apply, you need to mirror those devices for redundancy. https://openzfs.github.io/openzfs-docs/man/7/zpoolconcepts.7.html#Special_Allocation_Class https://openzfs.github.io/openzfs-docs/man/7/zpoolconcepts.7...
magicalhippo 3y ago
It's not about saving money, more about convenience and noise. With large SSDs it seems alluring that one could have the majority of hot data on SSDs, essentially making the cold data even colder. As you mention I could split my data in two, but that's a chore. If I need new data on the hot pool, I might have to first decide what got cold enough to move to the cold pool if there's not enough room left on the hot pool. That means I have to wait for that before I can save the new stuff on the hot pool. Searching for stuff means searching both places etc. I forgot I stumbled over AutoTier[1] which could work, but it seems abandoned so again, not ideal for precious data. And it's FUSE based, so performance is likely not the best. [1]: https://github.com/45Drives/autotier https://github.com/45Drives/autotier

the8472 3y ago

Having frequently used file metadata on SSDs while the cold parts are on HDDs would be noticeable even at home; the moment you start browsing the directory tree.

seized 3y ago
ZFS on Linux has exactly this, you can specify specific devices to hold metadata. Caveats apply, you need to mirror those devices for redundancy. https://openzfs.github.io/openzfs-docs/man/7/zpoolconcepts.7.html#Special_Allocation_Class https://openzfs.github.io/openzfs-docs/man/7/zpoolconcepts.7...

magicalhippo 3y ago

It's not about saving money, more about convenience and noise. With large SSDs it seems alluring that one could have the majority of hot data on SSDs, essentially making the cold data even colder. As you mention I could split my data in two, but that's a chore. If I need new data on the hot pool, I might have to first decide what got cold enough to move to the cold pool if there's not enough room left on the hot pool. That means I have to wait for that before I can save the new stuff on the hot pool. Searching for stuff means searching both places etc. I forgot I stumbled over AutoTier[1] which could work, but it seems abandoned so again, not ideal for precious data. And it's FUSE based, so performance is likely not the best. [1]: https://github.com/45Drives/autotier https://github.com/45Drives/autotier