Thumbs up for your effort and nice explanations. Did a dd on my ZFS pool with your script while watching the rest of the video. :-) Hope buyers on eBay will recognize true value you put in your store. For example - used/refurbished/new/open-box... mean very little in comparison to buying an item that has "just been thoroughly tested by someone who knows something about this stuff so you can count that this item is not being a bottleneck in a case of weird issues or unsufficient performance". Especially in a used items market where enthusiasts are testing enterprise equipment. Subscribed.
Great job. I want to migrate from HW RAID to TrueNAS SCALE (RAIDZ2) and this is a very usefull source of information about expected performance :) BTW: Thanx for ebay shop too, im for shure your happy customer.
Why are reads slower than writes? When a write occurs, we don't have to wait for it to complete and can move on to another task. For a read, we initiate the read and then must wait for the results. Writes can overlap with multiple disks, and reads must occur sequentially.
@ArtofServer Higher orders of software can do this, but not most OS's. Specialized copy SW can do this, but most rely on multiple threads to get overlapped reads
Read ahead caches on NAS's work this way. When a read occurs, they do another read while the previous data is transferred to the requester (probably over ethernet). When the next (sequential) read comes in , part of the read is already in progress. DD is not this smart
LSI 9201-16i performs well, and is better suited to saturate the PCIe 2.0 x8 bus when using HDDs. The PCIe 2.0 x8 gives you about 4GB/s bandwidth, which is about 32Gbps. Since HDDs usually top out at around 2Gbps, 2Gbps x16=32Gbps. The only drawback of the 9201-16i is that it's very expensive so it costs more than getting 2x 9201-8i cards.
Thumbs up for your effort and nice explanations. Did a dd on my ZFS pool with your script while watching the rest of the video. :-)
Hope buyers on eBay will recognize true value you put in your store. For example - used/refurbished/new/open-box... mean very little in comparison to buying an item that has "just been thoroughly tested by someone who knows something about this stuff so you can count that this item is not being a bottleneck in a case of weird issues or unsufficient performance". Especially in a used items market where enthusiasts are testing enterprise equipment.
Subscribed.
Thank you so much for your compliments! I hope my channel will continue to provide valuable information to other server enthusiasts!
What is the version of ZFS?
Did You try to do again tests with newly released 0.8.3 ?
Great job. I want to migrate from HW RAID to TrueNAS SCALE (RAIDZ2) and this is a very usefull source of information about expected performance :)
BTW: Thanx for ebay shop too, im for shure your happy customer.
Thank you! Glad this was helpful for you 😊
Pretty neat
Thanks for watching!
Why are reads slower than writes? When a write occurs, we don't have to wait for it to complete and can move on to another task. For a read, we initiate the read and then must wait for the results. Writes can overlap with multiple disks, and reads must occur sequentially.
can you reassemble the I/O requests for the reads out of order? and hence asynchronously?
@ArtofServer Higher orders of software can do this, but not most OS's. Specialized copy SW can do this, but most rely on multiple threads to get overlapped reads
Read ahead caches on NAS's work this way. When a read occurs, they do another read while the previous data is transferred to the requester
(probably over ethernet). When the next (sequential) read comes in , part of the read is already in progress. DD is not this smart
It would be nice if you provided a read only link to your analysis spreadsheet so I can print it out and read it in detail in my reading room (toilet)
Did you every find out if there was any way to increase the last columns numbers even a little bit. Thank you
add l2cache can increase random read speed
L2 cache? As in CPU L2 cache? Or do you mean L2ARC with ZFS?
@@ArtofServer yes I mean l2arc... How to add l2cache in CPU any way?
Hi, great video! how would the 16 port LSI 9201-16i preform?
LSI 9201-16i performs well, and is better suited to saturate the PCIe 2.0 x8 bus when using HDDs. The PCIe 2.0 x8 gives you about 4GB/s bandwidth, which is about 32Gbps. Since HDDs usually top out at around 2Gbps, 2Gbps x16=32Gbps. The only drawback of the 9201-16i is that it's very expensive so it costs more than getting 2x 9201-8i cards.