slow background sync

[Andreas Jung]

I installed ArangoDB 3.4.6-1 on a fresh customer machine (decent hardware).

During a batch import I see the import sometimes pausing for a while - obviously to slow

syncing. The iowait is pretty high with 60 to 90%.

2019-06-19T06:30:35Z [29067] WARNING {engines} slow background settings sync: 0.811185 s
2019-06-19T06:31:19Z [29067] WARNING {engines} slow background settings sync: 2.920207 s
2019-06-19T06:32:50Z [29067] WARNING {engines} slow background settings sync: 7.746773 s
2019-06-19T06:34:31Z [29067] WARNING {engines} slow background settings sync: 44.439727 s
2019-06-19T06:35:48Z [29067] WARNING {engines} slow background settings sync: 0.878996 s
2019-06-19T06:37:12Z [29067] WARNING {engines} slow background settings sync: 74.614215 s
2019-06-19T06:37:51Z [29067] WARNING {engines} slow background settings sync: 1.906352 s
2019-06-19T06:38:07Z [29067] WARNING {engines} slow background settings sync: 13.737372 s
2019-06-19T06:38:38Z [29067] WARNING {engines} slow background settings sync: 0.951346 s
2019-06-19T06:40:46Z [29067] WARNING {engines} slow background settings sync: 125.158793 s

I have not seen this behavior with the same set and same dataset on two other machines (all virtual machines).

Issue with the local storage subsystem?

Andreas