I have OpenBSD 6.1 DomU installed on Debian Dom0 host. Today I found issue with one of partitions (where mirror files were).
It says Input/output error when I'm trying access it after mount. However fsck does not complain: # fsck_ffs -f /dev/sd1a ** /dev/rsd1a ** File system is already clean ** Last Mounted on /open ** Phase 1 - Check Blocks and Sizes ** Phase 2 - Check Pathnames ** Phase 3 - Check Connectivity ** Phase 4 - Check Reference Counts ** Phase 5 - Check Cyl groups 725254 files, 94046365 used, 119012257 free (213185 frags, 14849884 blocks, 0.1% fragmentation) And dd gives me an error: # dd if=/dev/sd1a of=/dev/null bs=1m dd: /dev/sd1a: Input/output error 0+0 records in 0+0 records out 0 bytes transferred in 0.012 secs (0 bytes/sec) I tried to copy with dd on Dom0 and it was successful. Dom0 config (I'm using LVM logical volumes for hda and hdb): cat /etc/xen/mirror.openbsd.org.cfg builder = "hvm" memory = 2048 vcpus = 2 name = "mirror.openbsd.org" disk = [ '/dev/xen_domU/mirror.openbsd.org-disk,raw,hda,w', '/dev/xen_domU/mirror.openbsd.org-storage,raw,hdb,w'] boot = "c" # Boot to hard disk image vif = [ mac=00:17:3E:50:FD:99,bridge=xenbr0' ] usbdevice = 'tablet' vnc = 1 stdvga=1 videoram=16 # cat /etc/fstab 9c43dedec3141fca.b none swap sw 9c43dedec3141fca.a / ffs rw 1 1 9cee670113714c9d.a /open ffs rw 1 1 # ls -lah /open/ total 8 drwxr-xr-x 2 root wheel 512B Apr 3 2016 . drwxr-xr-x 15 root wheel 512B Apr 17 15:15 .. # vi /etc/fstab # disklabel sd0 # /dev/rsd0c: type: ESDI disk: ESDI/IDE disk label: QEMU HARDDISK duid: 9c43dedec3141fca flags: bytes/sector: 512 sectors/track: 63 tracks/cylinder: 255 sectors/cylinder: 16065 cylinders: 652 total sectors: 10485760 boundstart: 64 boundend: 10474380 drivedata: 0 16 partitions: # size offset fstype [fsize bsize cpg] a: 8401920 64 4.2BSD 2048 16384 1 # / b: 2072396 8401984 swap # none c: 10485760 0 unused # disklabel sd1 # /dev/rsd1c: type: ESDI disk: ESDI/IDE disk label: QEMU HARDDISK duid: 9cee670113714c9d flags: bytes/sector: 512 sectors/track: 63 tracks/cylinder: 255 sectors/cylinder: 16065 cylinders: 213879 total sectors: 3435978752 boundstart: 0 boundend: 3435978752 drivedata: 0 16 partitions: # size offset fstype [fsize bsize cpg] a: 3435978752 0 4.2BSD 8192 65536 1 # /open c: 3435978752 0 unused # mount /open/ # ls -lah /open/ ls: /open/: Input/output error # umount /open umount: /open: Input/output error # ls -lah / ls: open: Input/output error total 60720 drwxr-xr-x 15 root wheel 512B Apr 17 15:15 . drwxr-xr-x 15 root wheel 512B Apr 17 15:15 .. -rw-r--r-- 1 root wheel 578B Apr 2 2016 .cshrc -rw-r--r-- 1 root wheel 468B Apr 2 2016 .profile drwxr-xr-x 2 root wheel 512B Apr 1 22:38 altroot drwxr-xr-x 2 root wheel 1.0K Apr 1 22:38 bin -rw-r--r-- 1 root wheel 84.6K Apr 17 15:15 boot -rw-r--r-- 1 root wheel 10.3M Apr 17 15:10 bsd -rw-r--r-- 1 root wheel 9.0M Apr 17 15:10 bsd.rd -rw-r--r-- 1 root wheel 10.2M Apr 17 15:10 bsd.sp drwxr-xr-x 3 root wheel 19.5K Apr 17 15:57 dev drwxr-xr-x 25 root wheel 2.0K Apr 17 15:20 etc drwxr-xr-x 5 root wheel 512B Apr 1 22:38 home drwx-----T 2 root wheel 2.0K Apr 17 14:35 lost+found drwxr-xr-x 2 root wheel 512B Apr 1 22:38 mnt drwx------ 7 root wheel 512B Apr 1 22:38 root drwxr-xr-x 2 root wheel 1.5K Apr 1 22:38 sbin lrwxrwx--- 1 root wheel 11B Apr 1 22:38 sys -> usr/src/sys drwxrwxrwt 6 root wheel 512B Apr 17 16:00 tmp drwxr-xr-x 16 root wheel 512B Apr 1 23:05 usr drwxr-xr-x 23 root wheel 512B Apr 1 23:05 var # mount /dev/sd0a on / type ffs (local) /dev/sd1a on /open type ffs (local) # dmesg OpenBSD 6.1 (GENERIC.MP) #20: Sat Apr 1 13:45:56 MDT 2017 dera...@amd64.openbsd.org:/usr/src/sys/arch/amd64/compile/GENERIC.MP real mem = 2113925120 (2015MB) avail mem = 2045243392 (1950MB) mpath0 at root scsibus0 at mpath0: 256 targets mainbus0 at root bios0 at mainbus0: SMBIOS rev. 2.4 @ 0xfc001000 (12 entries) bios0: vendor Xen version "4.8.1-pre" date 01/23/2017 bios0: Xen HVM domU acpi0 at bios0: rev 2 acpi0: sleep states S3 S4 S5 acpi0: tables DSDT FACP APIC HPET WAET SSDT SSDT acpi0: wakeup devices acpitimer0 at acpi0: 3579545 Hz, 32 bits acpimadt0 at acpi0 addr 0xfee00000: PC-AT compat ioapic0 at mainbus0: apid 1 pa 0xfec00000, version 11, 48 pins cpu0 at mainbus0: apid 0 (boot processor) cpu0: Intel(R) Xeon(R) CPU X5660 @ 2.80GHz, 2793.35 MHz cpu0: FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CFLUSH,ACPI,MMX,FXSR,SSE,SSE2,HTT,SSE3,SSSE3,CX16,PCID,SSE4.1,SSE4.2,x2APIC,POPCNT,HV,NXE,PAGE1GB,RDTSCP,LONG,LAHF cpu0: 256KB 64b/line 8-way L2 cache cpu0: smt 0, core 0, package 0 mtrr: Pentium Pro MTRR support, 8 var ranges, 88 fixed ranges cpu0: apic clock running at 100MHz cpu1 at mainbus0: apid 2 (application processor) cpu1: Intel(R) Xeon(R) CPU X5660 @ 2.80GHz, 2793.05 MHz cpu1: FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CFLUSH,ACPI,MMX,FXSR,SSE,SSE2,HTT,SSE3,SSSE3,CX16,PCID,SSE4.1,SSE4.2,x2APIC,POPCNT,HV,NXE,PAGE1GB,RDTSCP,LONG,LAHF cpu1: 256KB 64b/line 8-way L2 cache cpu1: smt 0, core 1, package 0 acpihpet0 at acpi0: 62500000 Hz acpiprt0 at acpi0: bus 0 (PCI0) acpicpu0 at acpi0: C1(@1 halt!) acpicpu1 at acpi0: C1(@1 halt!) "PNP0F13" at acpi0 not configured "PNP0303" at acpi0 not configured "PNP0700" at acpi0 not configured "ACPI0007" at acpi0 not configured "ACPI0007" at acpi0 not configured pvbus0 at mainbus0: Xen 4.8 xen0 at pvbus0: features 0x2705, 32 grant table frames, event channel 1 xbf0 at xen0 backend 0 channel 6: disk scsibus1 at xbf0: 2 targets sd0 at scsibus1 targ 0 lun 0: <Xen, phy hda 768, 0000> SCSI3 0/direct fixed sd0: 5120MB, 512 bytes/sector, 10485760 sectors xbf1 at xen0 backend 0 channel 7: disk scsibus2 at xbf1: 2 targets sd1 at scsibus2 targ 0 lun 0: <Xen, phy hdb 832, 0000> SCSI3 0/direct fixed sd1: 1677724MB, 512 bytes/sector, 3435978752 sectors "vkbd" at xen0: device/vkbd/0 not configured xnf0 at xen0 backend 0 channel 8: address 00:17:3e:50:fd:99 pci0 at mainbus0 bus 0 pchb0 at pci0 dev 0 function 0 "Intel 82441FX" rev 0x02 pcib0 at pci0 dev 1 function 0 "Intel 82371SB ISA" rev 0x00 pciide0 at pci0 dev 1 function 1 "Intel 82371SB IDE" rev 0x00: DMA, channel 0 wired to compatibility, channel 1 wired to compatibility pciide0: channel 0 disabled (no drives) pciide0: channel 1 disabled (no drives) uhci0 at pci0 dev 1 function 2 "Intel 82371SB USB" rev 0x01: apic 1 int 23 piixpm0 at pci0 dev 1 function 3 "Intel 82371AB Power" rev 0x03: SMBus disabled xspd0 at pci0 dev 2 function 0 "XenSource Platform Device" rev 0x01 vga1 at pci0 dev 3 function 0 "Bochs VGA" rev 0x02 wsdisplay0 at vga1 mux 1: console (80x25, vt100 emulation) wsdisplay0: screen 1-5 added (80x25, vt100 emulation) isa0 at pcib0 isadma0 at isa0 fdc0 at isa0 port 0x3f0/6 irq 6 drq 2 fd0 at fdc0 drive 1: density unknown pckbc0 at isa0 port 0x60/5 irq 1 irq 12 pckbd0 at pckbc0 (kbd slot) wskbd0 at pckbd0: console keyboard, using wsdisplay0 pms0 at pckbc0 (aux slot) wsmouse0 at pms0 mux 0 pcppi0 at isa0 port 0x61 spkr0 at pcppi0 usb0 at uhci0: USB revision 1.0 uhub0 at usb0 configuration 1 interface 0 "Intel UHCI root hub" rev 1.00/1.00 addr 1 uhidev0 at uhub0 port 1 configuration 1 interface 0 "QEMU QEMU USB Tablet" rev 2.00/0.00 addr 2 uhidev0: iclass 3/0 ums0 at uhidev0: 3 buttons, Z dir wsmouse1 at ums0 mux 0 vscsi0 at root scsibus3 at vscsi0: 256 target softraid0 at root scsibus4 at softraid0: 256 targets root on sd0a (9c43dedec3141fca.a) swap on sd0b dump on sd0b Please advice for next troubleshooting steps. -- With regards, Evgeniy Sudyr