sdd/hdd config advice need

[capin]

hello
we have web server dual xeon 2696v2/256ram
2xssd intel dc 3710 200gb raid1
2xhdd hgst tale7200 6tb raid1
2xhdd toshiba mg4tb raid1
1 ssd m2 micron 7300 max 400gb
1 nvme consumer samsung 970 pro

we need advice
first
system on debian 10 and proxmox is goes to raid1 x dc 3710:200gb:
1. 500mb /boot
2. 50gb / system?
3. 150gb /lvm for lxc boot and system?
or 150gb system?

hdd raid1 4tb lvmraid4tb for main biggest internet project
hdd raid1 6tb lvmraid6tb for other small sites and servisrs

ssd micron is ext4 for mysql databases placement

sams 970 pro is for file caching. ( or maybe switch to enterprise for caching???

the 1st question is how to partition first small raid1 intel dc200gb -1. only for system and proxmox ?
or 2. system 50gb and other for lvm for boot and system other lxc ?

2nd question can we use hdd lvm for all boot and system and files of projects?
or better is placing lxc boot and system on lvm intel dc and other files on big hdd lvm?

 

[wolfgang]

Hi,

Proxmox VE needs no superfast OS disk. If you do not swap on this disk, a normal HDD is just fine.
If you use the default installation packages, 20GB is more than enough.

There is no concern about sharing OS and LXC/KVM on the same disk.
The only thing is the separation in the case of reinstallation.

 

[capin]

and how can we increase fsync of system . now iowait is very big.

 

[wolfgang]

Here the definition of IOWait:

- iowait: In a word, iowait stands for waiting for I/O to complete. But there
  are several problems:

  1. CPU will not wait for I/O to complete, iowait is the time that a task is
     waiting for I/O to complete. When CPU goes into idle state for
     outstanding task I/O, another task will be scheduled on this CPU.
  2. In a multi-core CPU, the task waiting for I/O to complete is not running
     on any CPU, so the iowait of each CPU is difficult to calculate.
  3. The value of iowait field in /proc/stat will decrease in certain
     conditions.

 

[capin]

in the munin monitoring we can see big iowait on the one of disk consumer ssd. if we change it to enterprise version can it help?

 

[wolfgang]

if we change it to enterprise version can it help?

Maybe. The question is, what is waiting.

i.e., restore a VM from a slow NFS server to a fast NVMe storage on PVE.
If you restore, the NVMe has nothing to do because it waits for io from the NFS.
But the IO will be huge because there is IOwait what does not affect the performance of the system.

 

[capin]

ok thank you!