Not every board can take ass-tons of RAM, and DDR4 RAM prices have gone markedly up in the last 2 years, not down. (There's even a fun price-fixing lawsuit or two in the works.)
You'd also need to buy a decently high-end chip to exceed 128 GB of RAM on your server. So while I agree the need for L2ARC in a number of situations has gone down, it's hardly limited to the "highly budget oriented plays." - Rich On Thu, Aug 23, 2018 at 8:42 PM, Jason Matthews <[email protected]> wrote: > > Maybe I am doing it wrong but I am using NVMe for primary storage and ass > tons of ram for arc. > > I think L2ARC is relegated to the highly budget oriented plays these days as > RAM is soooo cheap. Buy some more ram and fooor-get-about it. > > J. > > Sent from my iPhone > > On Aug 23, 2018, at 1:07 PM, Sanjay Nadkarni <[email protected]> > wrote: > > Found this link for FreeBSD too > http://www.brendangregg.com/blog/2015-03-10/freebsd-flame-graphs.html > > -Sanjay > > > > On 8/23/18 1:02 PM, Sanjay Nadkarni wrote: > > Would be useful if you could get flamegraphs when you run into this. See > https://github.com/brendangregg/FlameGraph > > Once we have that, the we can have a better understanding of what's going on > and we can dtrace it further to figure it out. > > -Sanjay > > > > On 8/23/18 5:47 AM, w.kruzel via openzfs-developer wrote: > > It's interesting what you said, as I have two examples (both with different > Intel nvme disks) that show otherwise. > > Being nvme, I was expecting read performance from L2ARC at 2GB/s+ levels, > yet I only get ~200MB/s read speeds when I certainly know it is being read > from L2ARC. > > When tested (details in my earlier post), I can get the same speed with > nvmecontrol perftest that is single threaded. > Multi threaded perftest gives 2GB/s + output. > > I also have this raised with FreeNAS where one of their devs tested it on > other make L2ARC he had installed and confirmed that it looks like single > threaded process. > > Can someone look into this please? > It is a major performance hit for L2ARC, making it not really fit for > purpose :( > > Kind regards, > Wojciech Kruzel > > > > openzfs / openzfs-developer / see discussions + participants + delivery > options Permalink ------------------------------------------ openzfs: openzfs-developer Permalink: https://openzfs.topicbox.com/groups/developer/Tf62628db027682f7-M3c0eb37c0f7387865d3eaa53 Delivery options: https://openzfs.topicbox.com/groups/developer/subscription
