Disable ext4 journaling and enable trim ext4 and SSD

Confirm that journaling is enabled and trim mount option is missing (default mount options).
> tune2fs -l /dev/nvme0n1

...
Filesystem features:      has_journal ext_attr resize_inode dir_index filetype extent 64bit flex_bg sparse_super large_file huge_file uninit_bg dir_nlink extra_isize
Filesystem flags:         signed_directory_hash
Default mount options:    user_xattr acl
...

> tune2fs -o discard /dev/nvme1n1
> tune2fs -O ^has_journal /dev/nvme1n1

Note that the ^ character is to toggle between enable/disable

> tune2fs -l /dev/nvme0n1

...
Filesystem features:      ext_attr resize_inode dir_index filetype extent 64bit flex_bg sparse_super large_file huge_file uninit_bg dir_nlink extra_isize
Filesystem flags:         signed_directory_hash
Default mount options:    user_xattr acl discard
...

Wanted to install mainline kernel 5 on my CentOS

> yum -y install https://www.elrepo.org/elrepo-release-7.0-4.el7.elrepo.noarch.rpm

> rpm --import https://www.elrepo.org/RPM-GPG-KEY-elrepo.org

> yum --enablerepo=elrepo-kernel install kernel-ml

> yum -y --enablerepo=elrepo-kernel install kernel-ml-{devel,headers,perf}

After a reboot, I uninstalled all other kernel versions e.g.

> yum remove kernel 

(if you wanted to install a kernel with long term support choose *-lt instead of *-ml) 

Interesting M.2 to PCIe NVME adapter cards & Samsung 970 Evo Plus benchmark

I am actually using two of the EZDIY-FAB cards, the form factor really makes the difference to me, but I also tried the Silverstone and Vantec card

• EZDIY-FAB Dual M.2 Adapter, M.2 PCIe NVMe and PCIe AHCI SSD to PCIe 3.0 x4 and M.2 SATA SSD to SATA III Adapter Card ($19 Amazon)
• Silverstone SST-ECM22 Dual M.2 to PCIe x4 NVMe SSD and SATA 6 G Adapter Card with Advanced Cooling ($33 Newegg)
•  Vantec M.2 NVMe/M.2 SATA SSD PCIe x4 Adapter ($19 Microcenter)

Also going to try the Jeyi card, I am interested to see if the claimed "high" quality components but still lowest price has any impact on performance

• JEYI SK7 M.2 NVMe SSD NGFF To PCI-E X4 Adapter M Key B Key Dual Interface Card Support PCI-E3.0 Dual Voltage 12V+3.3V SATA3 ($9 AliExpress)

Using Iozone, I got these MB/S values for writing a 64GB file on a 500GB Samsung 970 Evo Plus, the values are averages of 6 test runs, mounted in the EZDIY-FAB cards, ext4, CentOS 7, Kernel 5.011-1. No ext4 optimizations enabled.

reclen KB	write	rewrite	read	reread	random read	random write
4	942	915	2647	2849	73	843
16	947	918	3019	3029	231	871
128	913	905	3019	3024	838	859

I think these values are not far off from what public sources report for example: https://www.tomshardware.com/reviews/samsung-970-evo-plus-ssd,5608.html


Bunch of comparable cards..

• $17 RIITOP Dual M.2 to PCIe Adapter, M Key M.2 NVME AHCI SSD to PCI-e 3.0 x4 and B / B+M Key
• $35 SK16 PRO PCIE NVMe M-Key + AHCI B-Key + mSATA Adapter x16 PCI-E 3.0 Full Speed M.2 2280 aluminum
   
• $21 VANTEC UGT-M2PC200 M.2 NVMe + M.2 SATA SSD PCIe X4 Adapter
• $25 Rivo Dual M.2 SATA III and M2 to PCIe 3.0 X4 Adapter Card - Add M.2 SSD Devices to PC or Motherboard
• $19 Dual M.2 PCIe Adapter, M2 SSD NVME (m key) or SATA (b key) 22110 2280 2260 2242 2230 to PCI-e 3.0 x4 Host Controller Expansion Card
• $18 Dual M.2 PCIe Adapter M2 SSD NVME m key or SATA b key 22110 2280 2260 2242 2230 to PCI-e 3.0 x 4 Host Controller Expansion Card with
•  $17 ALLOYSEED PCI-E 4X to NGFF SSD Adapter Card B+M-key M.2 NGFF sata base ssd +NVME pcie ssd

Bunch of specialty cards:

• $299 SuperMicro AOC-SLG3-2E4 NVme PCIe card
• $199 https://www.amazon.com/Supermicro-AOC-SHG3-4M2P-Add-on-Card/dp/B07FYSZR6L
• $89 https://www.delock.de/produkte/G_62704/merkmale.html?setLanguage=en
• ???$ http://amfeltec.com/products/pci-express-gen-3-carrier-board-for-m-2-ssd
• $399 HighPoint SSD7101A-1 4x dedicated 32Gbps M.2 Ports to PCIe 3.0 x16 RAID
  Controller
• $149 https://store.squirrelsresearch.com/sqrl/acorn-nest-x4 (not sure if compatible to SSDs)

EZDIY-FAB Dual M.2 Adapter

Looking to test f2fs with my NVME Flash Drive

> yum install epel-release
> yum --enablerepo=epel-testing install f2fs-tools

Install Glances on CentOS

I really like Glances as a resource monitor for my Linux installation. Here is how to do:

> yum install -y epel-release
> yum install -y python-pip python-devel
> pip install --upgrade pip
> pip install glances

So we can run glances as a web service
> pip install bottle

I think I am going to try using Glances with Grafana: https://www.tecmint.com/install-glances-influxdb-grafana-to-monitor-centos-7/

Installing Iozone on CentOS 7

I followed these instructions: http://repoforge.org/use/


> yum install http://repository.it4i.cz/mirrors/repoforge/redhat/el7/en/x86_64/rpmforge/RPMS/rpmforge-release-0.5.3-1.el7.rf.x86_64.rpm

> yum install --enablerepo=rpmforge-extras iozone


Install from sources:

cd /opt

wget http://www.iozone.org/src/current/iozone3_490.tar

tar -xvf iozone3_490.tar
cd iozone3_490/src/current
make linux-AMD64

Getting rid of old CentOS kernels

> yum install yum-utils -y
> package-cleanup --oldkernels --count=1 -y