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turtle
Lord of the Rant.
Formerly turtle2472
 
Join Date: Mar 2005
Location: Upstate South Carolina
 
2022-08-23, 09:44

Yeah, I didn't dig in on the commands fully either but used them as a "general test" based on this blog post I found.

I should try with random too just for comparison...
Code:
[root@knowsmore ~]# sync; dd if=/dev/zero of=tempfile bs=1M count=1024; sync 1024+0 records in 1024+0 records out 1073741824 bytes (1.1 GB, 1.0 GiB) copied, 0.297927 s, 3.6 GB/s [root@knowsmore ~]# sync; dd if=/dev/random of=tempfile bs=1M count=1024; sync 1024+0 records in 1024+0 records out 1073741824 bytes (1.1 GB, 1.0 GiB) copied, 2.4137 s, 445 MB/s [root@knowsmore ~]# dd if=tempfile of=/dev/null bs=1M count=1024 1024+0 records in 1024+0 records out 1073741824 bytes (1.1 GB, 1.0 GiB) copied, 0.114965 s, 9.3 GB/s
There is a drastic difference between zero and random on this DB server (on a NMVe drive). Makes me think it has more to do with the random function introducing a lag of some sort. I could be wrong, but that is WAY slower than I would expect. The DB server is basic CentOS 9 minimal with only a few applications actually running on it. Granted, the DB activity is relatively high, and it is already in production so there will be some actual use during the test... but close to a tenth of the original speed? Something is fishy there.

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