![]() ![]() Saving space through deduplication doesn't come for free. Good thing i got 16gb ram deduplication seems like a kewl feature, but i'm not sure i have enuff ram If your cache hit ratio is below 90%, you will see performance improvements by adding cache to the system in the form of RAM or SSD L2ARC (dedicated read cache devices in the pool). FreeNAS includes tools in the GUI and the command line to see cache utilization. The optimal cache size for an array tends to increase with the size of the array, but outside of that guidance, the only thing we can recommend is to measure and observe as you go. Neither of those scenarios are likely, but they are possible. You can have a 2TB array with 3 users that needs 1GB of cache, and a 500TB array with 50 users that need 8GB of cache. There are no good guidelines for how much cache a given storage size with a given number of simultaneous users will need. ZFS performance lives and dies by its caching. However, that’s just to satisfy the stability side of things. Beyond that 16GB is a safer minimum, and once you get past 100TB of storage, 32GB is recommended. 8GB of RAM will get you through the 24TB range. ZFS does require a base level of RAM to be stable, and the amount of RAM it needs to be stable does grow with the size of the storage. ![]() There’s a lot of advice about how RAM hungry ZFS is, how it requires massive amounts of RAM, an oft quoted number is 1GB RAM per TB of storage. If you are using plugins and/or jails, 12 GB is a better starting point. Perhaps it will be ok with backup i suppose for the older models that don't support ecc ram?įreeNAS requires 8 GB of RAM for the base configuration. If it’s only some level of annoying (slightly, moderately…) that you need to restore your ZFS system from backups, non-ECC RAM will fit the bill. If it’s imperative that your ZFS based system must always be available, ECC RAM is a requirement. Systems with ECC RAM will correct single bit errors on the fly, and will halt the system before they can do any damage to the array if multiple bit errors are detected. For this reason, I highly recommend the use of ECC RAM with “mission-critical” ZFS. However if a non-ECC memory module goes haywire, it can cause irreparable damage to your ZFS pool that can cause complete loss of the storage. This is very nice when dealing with large storage arrays as a 64TB pool can be mounted in seconds, even after a bad shutdown. Additionally, ZFS has no pre-mount consistency checker or tool that can repair filesystem damage. If your data is corrupted in memory before it is written, ZFS will happily write (and checksum) the corrupted data. ZFS does something no other filesystem you’ll have available to you does: it checksums your data, and it checksums the metadata used by ZFS, and it checksums the checksums. I’ve been involved in the FreeNAS community for many years and have seen people argue that ECC is required and others argue that it is a pointless waste of money. I’ve run ZFS with ECC RAM and I’ve run it without. ![]() This is probably the most contested issue surrounding ZFS (the filesystem that FreeNAS uses to store your data) today. I know ZFS functionality exists in some enterprise rackmount models ( ), but if they were bringing it to some desktop models that would be really interesting.ĮDIT: A brief video in English, but with not a lot of information, posted just today: ![]() This video in Chinese from QNAP is all about it, but I've no idea what they are saying An image at the bottom of this Hong Kong forum thread refers to models that? are QTS Hero compatible? Or what?ģ. At 00:50 they talk about why QNAP hasn't gone for BTRFS, and then go on to mention "plans" for ZFS coming to desktop models.Ģ. "QTS hero (a ZFS-based NAS operating system) features data inline deduplication and compression, end-to-end data integrity, greater reliability, and higher performance, making it especially useful for tackling video-editing challenges."Ģ. but seeing some references online to "QTS Hero" - a ZFS-based version of the operating system?ġ. ![]()
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