[GTALUG] Booting Fedora from M.2 Optane Nvme

[Russell]

With all the CPU cache fencing going on I thought it might be fun to fiddle with NVM express on Fedora 27.  My primary SSD on this z370-A, was/is in build limbo while I updated bios and waited for outcomes. 

I installed a 32gib module from Newegg ($90 delivered) and I booted from F27-workstation live on usb. I let the anaconda installer do the automatic partitioning. 5gib of the 32gib reported was left unallocated for over-provisioning.

First boot appeared to be twice as fast as on the SATA SSD. Three or four seconds to get to the gui login as opposed to 7 or 8 on the original drive.

Had to install hdparm from the repo.

# hdparm -tT --direct /dev/sda1 

/dev/sda1:
 Timing O_DIRECT cached reads:   930 MB in 2.00 seconds = 464.92 MB/sec
 Timing O_DIRECT disk reads: 1370 MB in  3.00 seconds = 456.30 MB/sec

# hdparm -tT --direct /dev/nvme0n1 

/dev/nvme0n1:
 Timing O_DIRECT cached reads:   2302 MB in  2.00 seconds = 1151.84 MB/sec
 Timing O_DIRECT disk reads: 3474 MB in  3.00 seconds = 1157.65 MB/sec

More info on Nvme with a nice diagram of the Linux storage stack here.

https://en.m.wikipedia.org/wiki/NVM_Express

I switched back to the original SSD. An os-probe mapped the device to /dev/dm-1 and I was able to remake grub.conf and add this install to the bootloader on that drive.

A couple of switches back and forth between drives and it looks like the 10% performance hit I had experienced after the microcode updates, is now somewhat reduced, +-5%. 

Guilding the lilly a bit, as I didn't have any day to day problems with performance. Although it's hard to name Intel's product actions around this issue a field of Lilly's. 


-- 
Russell