I have a problem with high cpu usage by TAPDISK in xenserver - to be precise - in xcp-ng, I've posted the problem on xcp-ng forum but I didn't recieved any valid help from the creators of xcp-ng (...). Any way, the problem is when exporting (copying) a VM from one host to anonther, or copy VM within the same server the copy speed is extremly slow. Extremly slow I mean few MB per second. I dig the interent I've found that high TAPDISK usage could be connected to TCP offload of NIC card, but I'm new to xenserver and IDK if this is the way. Problem is that I've already stared production, and I have a problem with slow export (slow backup).
the setup is:
- the test is within one dell r510 server with perc h700
- local storage (8x8TB wd reds)
- two raids - raid10 and raid5
- xen orchestra sits on raid10 volume
- DR backup test - from raid10 to raid5 volume
- Two Intel X5675 CPUS, 128 GB RAM
TAPDISK almost 100% cpu usage during export
x Top Processes Procs=0 mode=3 (1=Basic, 3=Perf 4=Size 5=I/O)qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqx
x PID %CPU Size Res Res Res Res Shared Faults Command x
x Used KB Set Text Data Lib KB Min Maj x
x 8432 95.8 46716 10604 228 7580 0 2884 0 0 tapdisk x
x 7346 44.7 5596512 362032 24020 5499448 0 24308 3 0 xapi x
x 105 5.0 0 0 0 0 0 0 0 0 kswapd0
Link to forum thread: https://xcp-ng.org/forum/topic/2036/extrlemy-slow-backup-speec-about-few-mb-s/20