did you use scripts to shuffle data around? or just have an unoptimized layout? with sas ssd its probably fine still
Enterprise SSD "small deals"
- Thread starter ca3y6
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I think RAIDZ2 is more computationally expensive than RAIDZ1 which should be a simple XOR. What sort of hardware (CPU/RAM speed/HBA) were you running this on?
16 cores with 256gb RAM. I’ve run these tests on different platforms, all the way from Ivy Bridge to Epyc. The results are the same, with minor variations.
That would only be an issue for writes though, the parity calculation isn't necessary on reads, just the checksum.
And this fits with my observations too, 2x 10-wide Z2 VDEVs give about 1.5GB/s if i dd a file to null for example.
64 cores & ~128GB 3200MT/s ddr4 passed to the VM along with a 9305 24i HBA.
Interestingly a scrub can do well above 3.2GB/s with peaks up to 4.5-5GB/s
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Doesn’t ZFS check the parity on reads as well? I thought that was a key data reliability feature of ZFS. Though I presume it can do that in a non blocking way.
It's read on scrubs, but otherwise not afaik. Unless the checksum fails. Better to spend the disk bandwidth on actual data reads?
From a performance point of view it makes sense. But from a “self-healing” point of view, if you check the checksum on the data but don’t check the parity, then you are exposed to rot in the parity data which will bite you the day you lose a disk.
Yeah, that's what scrubs are for, making sure you check all the data with the performance benefit of not having to read hotter (parity) data over and over and over again during normal operation.
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This leads me to believe the checksum is calculated again on read and compared to what was calculated when it was written.
OpenE Link
Maybe I misunderstood what was said and this already know
OpenE Link
Maybe I misunderstood what was said and this already know
That they hadn't yet failed at the time they were decommissioned.
I got the drives at last. Well, shipping to EU is not fast.
I surprisingly did not pay extra VAT. No idea how that happened. post claimed VAT has been payed even though I only payed the original price without VAT on top.
The drives were sold out long ago but I am attaching smartctl -a output in case anyone is interested. Seems from my unexperienced eyes the drives are fine with not much TBW.
Cool 
VAT up to specific value should be added automatically by eBay, so we (as in EU) do not pay for separately.
Its much more convenient to be handled by eBay/Amazon/etc (even if Aliexpress claiming they do), instead of us and makes buying easier for PC parts (as they should be excluded from duty in some countries, so we pay VAT only).
VAT up to specific value should be added automatically by eBay, so we (as in EU) do not pay for separately.
Its much more convenient to be handled by eBay/Amazon/etc (even if Aliexpress claiming they do), instead of us and makes buying easier for PC parts (as they should be excluded from duty in some countries, so we pay VAT only).