I never noticed this on TrueNAS Core 13.3, until I decided to create a new dataset. [16m-recordsize] I know that this has already been available to ZFS, but now it’s exposed by the GUI? Is this an oversight, or does iXsystems believe that 16-MiB recordsize is considered tried-and-true to allow f…

[image] Sara: 16 + 16 + 1 = 48 MiB If the blocks on the physical disk(s) consume 16 + 16 + 1 megabytes, then all three blocks, which comprise the file, consume a total of 33 megabytes. EDIT: Even for “uncompressible” files, ZFS’s inline compression (LZE, LZ4, ZSTD) will essentially squish th…

Sharing my current experience as I am running SCALE 24.04.2 as well and can see the option. In fact, i am using it right now for a brand new Plex media pool. I believe this thread summarises the pros and cons nicely and jive in with what I am seeing: the metadata usage will decrease the (sequenti…

I think I know why. Not at my computer, but will reply later.

[image] Tony-1971: Not tried (yet) I did on CORE, works great. Saved me a few hundred GB of space.

16MB record-size has been there for quite some time on scale, I wouldn’t recommend it over 1MB unless you have clear benefits to gain from it, ie compression ratio. for bulk storage of uncompressible files (ie video) 1MB is about ideal. 16MB comes with the caveat of quite big objects in kernel memo…

[image] RetroG: 16MB comes with the caveat of quite big objects in kernel memory, which can result in memory pressure/fragmentation issues that will mostly cause ARC to collapse during heavy I/O and the like… but since ARC uses already compressed records if your data is highly compressible this …

I did a quick test a month or two ago running 1 MiB vs. 4 MiB with synthetics and found 4 MiB introduced a bit of a performance hit vs. 1 MiB. It may just be a matter of other parts of the stack not being used to it, or some interaction that is antagonistic to caches… didn’t deep dive on it. 4 MiB i…

I also think if you are jumping around a large file… say seeking a video… zfs is going to have to read 16MB in order to verify a checksum before returning a frame… which may be much less than 16MB.

That’s actually an interesting point! Though, I think much of it is mitigated with modern video players, such as MPV and VLC, which preload much of the video over the local network, even if you haven’t skipped ahead from the beginning. So, in theory, if you “seek around” near the current playback …

16 MiB recordsize?!?!?!?! <--- clickbait punctuation marks for the algorithm

TrueNAS General

Davvo September 11, 2024, 4:08pm 12

I will post some testing once I get my case.

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16 MiB recordsize?!?!?!?! <--- clickbait punctuation marks for the algorithm

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