slow write speeds still :cry:

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Re: slow write speeds still :cry:

Postby lundman » Mon Apr 23, 2018 4:02 pm

Ah yep, disappointing.
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Re: slow write speeds still :cry:

Postby e8wwv » Tue Apr 24, 2018 6:09 pm

lundman wrote:Ah yep, disappointing.



fwiw, I was getting ~90MB/s for the same operation under 1.7.0 (vs 59-61MB/s now).

The latest master following all the april updates seems to be less prone to choking on simultaneous activity at the expense of a lower 'top speed' vs 1.7.0. If that makes any sense. For example torrent activity doesnt seem to choke it as much but writing a tape is slower, was 4.5-6h in december now 11-11.5h for a full lto6.

is it possible or useful to 'ask for assistance' from other openzfs porting groups? seems like this port is not keeping up. given past performance it seems like something went wrong as far back as 2015. is it not reasonable to assume that every change since then needs to be reexamined? there must be a way to script the benchmarking of each commit since day 1. I was trying to suggest this earlier in the thread but that suggestion appears to have caused a problem for someone.
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Re: slow write speeds still :cry:

Postby lundman » Wed Apr 25, 2018 6:51 pm

We are actually immediately behind illumos in terms of commits, so ahead of ZOL and FBSD. But this does appear to be something specific to this port, and it happened some time back. I can certainly, and have been, ask those devs for insights, but getting them to actually try the osx port has been impossible. I know Brendon tried all binary releases we had, in various combinations to get a feel for the progression. Ultimately, it may just been that we calmed it down a bit, as during heavy ZFS loads it would stutter the mouse, which many GUI users disliked, for some reason.. But it is ongoing still - we have also started looking at ZOL's assembler replacement code, and see if that can also help.
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Re: slow write speeds still :cry:

Postby macz » Thu Apr 26, 2018 6:14 am

I run a backup server on OS X with 1.4.5 I think but also run my primary server as a esxi all-in-one with a omniosCE / napp-it storage VM providing 2 pools .. one for VMs on stripped S3500 SSD and a data/backup pool with 4x stripped 8TB spinners...

I too have noticed in ominos/illumos similar bad intrapool transfer speeds. a copy from the data pool to the ssd pool (no a sync write operation) as its done from the command line of ominos showed pretty pitiful throughput ...

so perhaps this is an inherited performance issue from the illumos master
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Re: slow write speeds still :cry:

Postby lundman » Thu Apr 26, 2018 4:08 pm

They did add the write-throttle. the idea is that a single stream can not starve out all IO. But in theory, you can start a second terminal, and get a second copy going and both will do "well".
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