Hardware: Intel SB2600WTTR, 2x Xeon E5-2670v3, 96Gb RAM, 12x Seagate 900Gb 10K in RAID5 (LSI MegaRAID SAS Invader Controller).
Software: VMWare vSphere ESXi 6.0.0-20150902001-standard.
VM: Debian Linux 8.9 (kernel 3.16.0-4-amd64)
Problem is in very slow disk perfomance. hdparm -tT /dev/sda says:
Timing cached reads: 16950 MB in 2.00 seconds = 8481.87 MB/sec
Timing buffered disk reads: 218 MB in 3.45 seconds = 63.11 MB/sec
For example, restoring MySQL database using myloader gives 7-10 MB/s of disk usage ( iotop -o says). Restoring files from tar archive gives similar values (10-12 MB/s). Sometimes VM "stucks" for a minute, with no errors in logs, then resumes file operations.
Found this article: ESXI 6.5 Storage Performance Issues and Fix | opvizor.com - it recommends unload vmware ahci driver. In my case esxcli software vib list | grep ahci gives only:
sata-ahci 3.0-22vmw.600.1.17.3029758 VMware VMwareCertified 2017-09-26
Created new VM with linux - same result.
