Comment 34 for bug 1833618

@Rhyan, thanks for the quick pointers, helped a lot =), I think I found out what is going on.

Linux mylab 5.0.0-30-generic #32-Ubuntu SMP Wed Sep 18 00:24:43 UTC 2019 aarch64 aarch64 aarch64 GNU/Linux

Using a memstick in an aarch64 server:

$ sudo sg_inq -d /dev/sdb

standard INQUIRY:
  PQual=0 Device_type=0 RMB=1 LU_CONG=0 version=0x06 [SPC-4]
  [AERC=0] [TrmTsk=0] NormACA=0 HiSUP=0 Resp_data_format=2
  SCCS=0 ACC=0 TPGS=0 3PC=0 Protect=0 [BQue=0]
  EncServ=0 MultiP=0 [MChngr=0] [ACKREQQ=0] Addr16=0
  [RelAdr=0] WBus16=0 Sync=0 [Linked=0] [TranDis=0] CmdQue=0
    length=36 (0x24) Peripheral device type: disk
 Vendor identification: Corsair
 Product identification: Voyager Mini 3.0
 Product revision level: 000B
 Unit serial number: 0C7707865010

command sg_inq returns right away with proper info and, with 60-persistent-storage.rules only:

$ sudo udevadm info --query=all --name=/dev/sdb | grep -i serial
E: ID_SERIAL=Corsair_Voyager_Mini_3.0_070851D0E490C776-0:0
E: ID_SERIAL_SHORT=070851D0E490C776

--------

$ sudo sg_inq -d /dev/sdb

<hangs for quite sometime>

$ sudo udevadm info --query=all --name=/dev/sdb | grep -i serial

<no serial is given>

AFTER sg_inq command returns (10 seconds or more) AND with 55-scsi-sg3.rules installed, then we get:

$ sudo udevadm info --query=all --name=/dev/sdb | grep -i serial
E: ID_SERIAL=3
E: ID_SERIAL_SHORT=2000acde48234567

Which means that its likely that curtin did not wait enough (or settled) for the device VPD to "arrive". I haven't found out why the "USB" ("SCSI") vpd gets so long to be returned when sg-utils-udev is installed, will investigate.