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linux:fs:zfs:dedup [2021/02/15 11:39] – niziaklinux:fs:zfs:dedup [2021/02/17 08:07] – niziak
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 [[https://superuser.com/questions/1169139/zfs-dedupe-again-is-memory-usage-dependent-on-physical-deduped-compressed|ZFS dedupe (again): Is memory usage dependent on physical (deduped, compressed) data stored or on logical used?]] [[https://superuser.com/questions/1169139/zfs-dedupe-again-is-memory-usage-dependent-on-physical-deduped-compressed|ZFS dedupe (again): Is memory usage dependent on physical (deduped, compressed) data stored or on logical used?]]
  
 +
 +===== THINK TWICE ! =====
 +
 +Never ever turn on deduplication for whole pool. It is not possible to turn it off without sending whole pool to another zfs and receiving it back.
 +Also it is best to have plenty of RAM to fit all DDT into RAM, not SSD/NVMe.
 +
 +Huge CPU usage by over 96 ZFS kernel threads noticed with open-zfs v8.0.6 (ZFS On Linux), when some big parts of data deleted (auto snapshot rotation). It is connected with deduplication enabled and causes system to almost freeze because of high CPU usage!