我连接了 USB (ext4) 驱动器，并且它已在 /etc/fstab 中注册。它可以很好地安装在 /media/Backup 处。我想使用绑定/环回安装在该驱动器上安装特定目录（这是我正在使用的备份软件所必需的）。
我的 /etc/fstab 如下，但每当我sudo mount -a/Volumes 挂载两次（通过 webmin 查看）时，一次作为环回（但未使用），第二次作为附加 ext4 挂载，其 UID 与 /media/ 的挂载点相同备份（按使用时安装）。
$ cat /etc/fstab
proc /proc proc defaults 0 0
/dev/mmcblk0p1 /boot vfat defaults 0 2
/dev/mmcblk0p2 / ext4 defaults,noatime 0 1
# a swapfile is not a swap partition, so no using swapon|off from here on, use dphys-swapfile swap[on|off] for that
UUID=922878f3-259a-48f6-b9a6-69563389a354 /media/Backup ext4 defaults 0 0
/media/Backup/_CrashPlan/Hackintosh-Pro/Volumes /Volumes none bind 0 0
我确信我过去已经在没有我的 debian 自动挂载 ext4 的情况下完成了这个工作。在引导分区和操作系统分区崩溃后，我不得不重新安装系统。
这是 dmesg 的副本，但我似乎无法从中找到任何有用的信息。
$ dmesg
[ 0.000000] Booting Linux on physical CPU 0x0
[ 0.000000] Initializing cgroup subsys cpu
[ 0.000000] Initializing cgroup subsys cpuacct
[ 0.000000] Linux version 3.12.28+ (dc4@dc4-XPS13-9333) (gcc version 4.8.3 20140303 (prerelease) (crosstool-NG linaro-1.13.1+bzr2650 - Linaro GCC 2014.03) ) #709 PREEMPT Mon Sep 8 15:28:00 BST 2014
[ 0.000000] CPU: ARMv6-compatible processor [410fb767] revision 7 (ARMv7), cr=00c5387d
[ 0.000000] CPU: PIPT / VIPT nonaliasing data cache, VIPT nonaliasing instruction cache
[ 0.000000] Machine: BCM2708
[ 0.000000] cma: CMA: reserved 8 MiB at 1d800000
[ 0.000000] Memory policy: ECC disabled, Data cache writeback
[ 0.000000] On node 0 totalpages: 122880
[ 0.000000] free_area_init_node: node 0, pgdat c061dd90, node_mem_map c06cf000
[ 0.000000] Normal zone: 960 pages used for memmap
[ 0.000000] Normal zone: 0 pages reserved
[ 0.000000] Normal zone: 122880 pages, LIFO batch:31
[ 0.000000] pcpu-alloc: s0 r0 d32768 u32768 alloc=1*32768
[ 0.000000] pcpu-alloc: [0] 0
[ 0.000000] Built 1 zonelists in Zone order, mobility grouping on. Total pages: 121920
[ 0.000000] Kernel command line: dma.dmachans=0x7f35 bcm2708_fb.fbwidth=656 bcm2708_fb.fbheight=416 bcm2708.boardrev=0xe bcm2708.serial=0xa634c3b9 smsc95xx.macaddr=B8:27:EB:34:C3:B9 sdhci-bcm2708.emmc_clock_freq=250000000 vc_mem.mem_base=0x1ec00000 vc_mem.mem_size=0x20000000 dwc_otg.lpm_enable=0 console=ttyAMA0,115200 console=tty1 root=/dev/mmcblk0p2 rootfstype=ext4 elevator=deadline rootwait
[ 0.000000] PID hash table entries: 2048 (order: 1, 8192 bytes)
[ 0.000000] Dentry cache hash table entries: 65536 (order: 6, 262144 bytes)
[ 0.000000] Inode-cache hash table entries: 32768 (order: 5, 131072 bytes)
[ 0.000000] Memory: 472044K/491520K available (4498K kernel code, 242K rwdata, 1344K rodata, 143K init, 701K bss, 19476K reserved)
[ 0.000000] Virtual kernel memory layout:
[ 0.000000] vector : 0xffff0000 - 0xffff1000 ( 4 kB)
[ 0.000000] fixmap : 0xfff00000 - 0xfffe0000 ( 896 kB)
[ 0.000000] vmalloc : 0xde800000 - 0xff000000 ( 520 MB)
[ 0.000000] lowmem : 0xc0000000 - 0xde000000 ( 480 MB)
[ 0.000000] modules : 0xbf000000 - 0xc0000000 ( 16 MB)
[ 0.000000] .text : 0xc0008000 - 0xc05bca24 (5843 kB)
[ 0.000000] .init : 0xc05bd000 - 0xc05e0eac ( 144 kB)
[ 0.000000] .data : 0xc05e2000 - 0xc061e8a0 ( 243 kB)
[ 0.000000] .bss : 0xc061e8ac - 0xc06ce080 ( 702 kB)
[ 0.000000] SLUB: HWalign=32, Order=0-3, MinObjects=0, CPUs=1, Nodes=1
[ 0.000000] Preemptible hierarchical RCU implementation.
[ 0.000000] NR_IRQS:394
[ 0.000000] sched_clock: 32 bits at 1000kHz, resolution 1000ns, wraps every 4294967ms
[ 0.000000] Switching to timer-based delay loop
[ 0.000000] Console: colour dummy device 80x30
[ 0.000000] console [tty1] enabled
[ 0.001171] Calibrating delay loop (skipped), value calculated using timer frequency.. 2.00 BogoMIPS (lpj=10000)
[ 0.001233] pid_max: default: 32768 minimum: 301
[ 0.001752] Mount-cache hash table entries: 512
[ 0.002568] Initializing cgroup subsys memory
[ 0.002679] Initializing cgroup subsys devices
[ 0.002717] Initializing cgroup subsys freezer
[ 0.002749] Initializing cgroup subsys blkio
[ 0.002897] CPU: Testing write buffer coherency: ok
[ 0.003362] Setting up static identity map for 0xc04487f8 - 0xc0448854
[ 0.005297] devtmpfs: initialized
[ 0.021294] VFP support v0.3: implementor 41 architecture 1 part 20 variant b rev 5
[ 0.022872] NET: Registered protocol family 16
[ 0.028149] DMA: preallocated 4096 KiB pool for atomic coherent allocations
[ 0.028831] cpuidle: using governor ladder
[ 0.028880] cpuidle: using governor menu
[ 0.029280] bcm2708.uart_clock = 0
[ 0.031364] hw-breakpoint: found 6 breakpoint and 1 watchpoint registers.
[ 0.031424] hw-breakpoint: maximum watchpoint size is 4 bytes.
[ 0.031459] mailbox: Broadcom VideoCore Mailbox driver
[ 0.031556] bcm2708_vcio: mailbox at f200b880
[ 0.031661] bcm_power: Broadcom power driver
[ 0.031700] bcm_power_open() -> 0
[ 0.031724] bcm_power_request(0, 8)
[ 0.532443] bcm_mailbox_read -> 00000080, 0
[ 0.532482] bcm_power_request -> 0
[ 0.532740] Serial: AMBA PL011 UART driver
[ 0.532915] dev:f1: ttyAMA0 at MMIO 0x20201000 (irq = 83, base_baud = 0) is a PL011 rev3
[ 0.891387] console [ttyAMA0] enabled
[ 0.918512] bio: create slab <bio-0> at 0
[ 0.924043] SCSI subsystem initialized
[ 0.928045] usbcore: registered new interface driver usbfs
[ 0.933750] usbcore: registered new interface driver hub
[ 0.939311] usbcore: registered new device driver usb
[ 0.945887] Switched to clocksource stc
[ 0.950165] FS-Cache: Loaded
[ 0.953329] CacheFiles: Loaded
[ 0.969238] NET: Registered protocol family 2
[ 0.975043] TCP established hash table entries: 4096 (order: 3, 32768 bytes)
[ 0.982456] TCP bind hash table entries: 4096 (order: 2, 16384 bytes)
[ 0.989048] TCP: Hash tables configured (established 4096 bind 4096)
[ 0.995496] TCP: reno registered
[ 0.998790] UDP hash table entries: 256 (order: 0, 4096 bytes)
[ 1.004660] UDP-Lite hash table entries: 256 (order: 0, 4096 bytes)
[ 1.011434] NET: Registered protocol family 1
[ 1.016421] RPC: Registered named UNIX socket transport module.
[ 1.022380] RPC: Registered udp transport module.
[ 1.027187] RPC: Registered tcp transport module.
[ 1.031910] RPC: Registered tcp NFSv4.1 backchannel transport module.
[ 1.039245] bcm2708_dma: DMA manager at f2007000
[ 1.043986] bcm2708_gpio: bcm2708_gpio_probe c05efef0
[ 1.049558] vc-mem: phys_addr:0x00000000 mem_base=0x1ec00000 mem_size:0x20000000(512 MiB)
[ 1.059141] audit: initializing netlink socket (disabled)
[ 1.064650] type=2000 audit(0.910:1): initialized
[ 1.234986] VFS: Disk quotas dquot_6.5.2
[ 1.239352] Dquot-cache hash table entries: 1024 (order 0, 4096 bytes)
[ 1.248321] FS-Cache: Netfs 'nfs' registered for caching
[ 1.255230] NFS: Registering the id_resolver key type
[ 1.260520] Key type id_resolver registered
[ 1.264730] Key type id_legacy registered
[ 1.269540] msgmni has been set to 937
[ 1.275280] Block layer SCSI generic (bsg) driver version 0.4 loaded (major 252)
[ 1.283145] io scheduler noop registered
[ 1.287224] io scheduler deadline registered (default)
[ 1.292706] io scheduler cfq registered
[ 1.297923] BCM2708FB: allocated DMA memory 5dc00000
[ 1.302967] BCM2708FB: allocated DMA channel 0 @ f2007000
[ 1.310788] bcm2708_fb_pan_display(0,0) returns=0
[ 1.313093] Console: switching to colour frame buffer device 82x26
[ 1.313640] bcm2708_fb_pan_display(0,0) returns=0
[ 1.336543] bcm2708-dmaengine bcm2708-dmaengine: Load BCM2835 DMA engine driver
[ 1.345568] uart-pl011 dev:f1: no DMA platform data
[ 1.352555] vc-cma: Videocore CMA driver
[ 1.357922] vc-cma: vc_cma_base = 0x00000000
[ 1.363955] vc-cma: vc_cma_size = 0x00000000 (0 MiB)
[ 1.370708] vc-cma: vc_cma_initial = 0x00000000 (0 MiB)
[ 1.386998] brd: module loaded
[ 1.396710] loop: module loaded
[ 1.401419] vchiq: vchiq_init_state: slot_zero = 0xdd800000, is_master = 0
[ 1.410729] Loading iSCSI transport class v2.0-870.
[ 1.418279] usbcore: registered new interface driver smsc95xx
[ 1.425829] dwc_otg: version 3.00a 10-AUG-2012 (platform bus)
[ 1.633146] Core Release: 2.80a
[ 1.637676] Setting default values for core params
[ 1.643746] Finished setting default values for core params
[ 1.850680] Using Buffer DMA mode
[ 1.855291] Periodic Transfer Interrupt Enhancement - disabled
[ 1.862454] Multiprocessor Interrupt Enhancement - disabled
[ 1.869385] OTG VER PARAM: 0, OTG VER FLAG: 0
[ 1.875042] Dedicated Tx FIFOs mode
[ 1.880167] WARN::dwc_otg_hcd_init:1042: FIQ DMA bounce buffers: virt = 0xddc14000 dma = 0x5dc14000 len=9024
[ 1.892656] FIQ FSM acceleration enabled for :
[ 1.892656] Non-periodic Split Transactions
[ 1.892656] Periodic Split Transactions
[ 1.892656] High-Speed Isochronous Endpoints
[ 1.914547] dwc_otg: Microframe scheduler enabled
[ 1.914642] WARN::hcd_init:473: FIQ at 0xc0321550
[ 1.920751] WARN::hcd_init:474: FIQ ASM at 0xc0321800 length 36
[ 1.928068] WARN::hcd_init:500: MPHI regs_base at 0xde806000
[ 1.935059] dwc_otg bcm2708_usb: DWC OTG Controller
[ 1.941308] dwc_otg bcm2708_usb: new USB bus registered, assigned bus number 1
[ 1.949957] dwc_otg bcm2708_usb: irq 32, io mem 0x00000000
[ 1.956822] Init: Port Power? op_state=1
[ 1.962013] Init: Power Port (0)
[ 1.966856] usb usb1: New USB device found, idVendor=1d6b, idProduct=0002
[ 1.974980] usb usb1: New USB device strings: Mfr=3, Product=2, SerialNumber=1
[ 1.983547] usb usb1: Product: DWC OTG Controller
[ 1.989578] usb usb1: Manufacturer: Linux 3.12.28+ dwc_otg_hcd
[ 1.996730] usb usb1: SerialNumber: bcm2708_usb
[ 2.003372] hub 1-0:1.0: USB hub found
[ 2.008597] hub 1-0:1.0: 1 port detected
[ 2.014269] dwc_otg: FIQ enabled
[ 2.014287] dwc_otg: NAK holdoff enabled
[ 2.014296] dwc_otg: FIQ split-transaction FSM enabled
[ 2.014316] Module dwc_common_port init
[ 2.014769] usbcore: registered new interface driver usb-storage
[ 2.022521] mousedev: PS/2 mouse device common for all mice
[ 2.030095] bcm2835-cpufreq: min=700000 max=700000 cur=700000
[ 2.037317] bcm2835-cpufreq: switching to governor powersave
[ 2.044226] bcm2835-cpufreq: switching to governor powersave
[ 2.051236] sdhci: Secure Digital Host Controller Interface driver
[ 2.058715] sdhci: Copyright(c) Pierre Ossman
[ 2.064387] sdhci: Enable low-latency mode
[ 2.106137] mmc0: SDHCI controller on BCM2708_Arasan [platform] using platform's DMA
[ 2.116683] mmc0: BCM2708 SDHC host at 0x20300000 DMA 2 IRQ 77
[ 2.124011] sdhci-pltfm: SDHCI platform and OF driver helper
[ 2.131194] ledtrig-cpu: registered to indicate activity on CPUs
[ 2.140837] hidraw: raw HID events driver (C) Jiri Kosina
[ 2.155191] usbcore: registered new interface driver usbhid
[ 2.162274] usbhid: USB HID core driver
[ 2.172153] TCP: cubic registered
[ 2.178933] Initializing XFRM netlink socket
[ 2.186679] NET: Registered protocol family 17
[ 2.192677] Key type dns_resolver registered
[ 2.206128] Indeed it is in host mode hprt0 = 00021501
[ 2.216042] registered taskstats version 1
[ 2.226654] Waiting for root device /dev/mmcblk0p2...
[ 2.396020] usb 1-1: new high-speed USB device number 2 using dwc_otg
[ 2.416098] Indeed it is in host mode hprt0 = 00001101
[ 2.427101] mmc0: could read SD Configuration register (SCR) at the 2th attempt
[ 2.468192] mmc0: read SD Status register (SSR) after 2 attempts
[ 2.489201] mmc0: new high speed SDHC card at address 0007
[ 2.506584] mmcblk0: mmc0:0007 SD16G 14.4 GiB
[ 2.517410] mmcblk0: p1 p2
[ 2.576747] EXT4-fs (mmcblk0p2): mounted filesystem with ordered data mode. Opts: (null)
[ 2.587867] VFS: Mounted root (ext4 filesystem) on device 179:2.
[ 2.596717] devtmpfs: mounted
[ 2.601690] Freeing unused kernel memory: 140K (c05bd000 - c05e0000)
[ 2.656519] usb 1-1: New USB device found, idVendor=0424, idProduct=9512
[ 2.665973] usb 1-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
[ 2.677305] hub 1-1:1.0: USB hub found
[ 2.682790] hub 1-1:1.0: 3 ports detected
[ 2.966211] usb 1-1.1: new high-speed USB device number 3 using dwc_otg
[ 3.076551] usb 1-1.1: New USB device found, idVendor=0424, idProduct=ec00
[ 3.085121] usb 1-1.1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
[ 3.099762] smsc95xx v1.0.4
[ 3.175786] smsc95xx 1-1.1:1.0 eth0: register 'smsc95xx' at usb-bcm2708_usb-1.1, smsc95xx USB 2.0 Ethernet, b8:27:eb:34:c3:b9
[ 3.296256] usb 1-1.3: new high-speed USB device number 4 using dwc_otg
[ 3.427385] usb 1-1.3: New USB device found, idVendor=1058, idProduct=1021
[ 3.446087] usb 1-1.3: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[ 3.455127] usb 1-1.3: Product: Ext HDD 1021
[ 3.473952] usb 1-1.3: Manufacturer: Western Digital
[ 3.486078] usb 1-1.3: SerialNumber: 57434156354B393330333835
[ 3.501956] usb-storage 1-1.3:1.0: USB Mass Storage device detected
[ 3.515608] scsi0 : usb-storage 1-1.3:1.0
[ 4.186424] udevd[158]: starting version 175
[ 4.528764] scsi 0:0:0:0: Direct-Access WD Ext HDD 1021 2002 PQ: 0 ANSI: 4
[ 4.556717] sd 0:0:0:0: [sda] 1953519616 512-byte logical blocks: (1.00 TB/931 GiB)
[ 4.589888] sd 0:0:0:0: [sda] Test WP failed, assume Write Enabled
[ 4.617007] sd 0:0:0:0: [sda] Asking for cache data failed
[ 4.624185] sd 0:0:0:0: [sda] Assuming drive cache: write through
[ 4.655375] sd 0:0:0:0: [sda] Test WP failed, assume Write Enabled
[ 4.685477] sd 0:0:0:0: [sda] Asking for cache data failed
[ 4.716072] sd 0:0:0:0: [sda] Assuming drive cache: write through
[ 4.726316] sd 0:0:0:0: Attached scsi generic sg0 type 0
[ 5.134184] sda: sda1
[ 5.144177] sd 0:0:0:0: [sda] Test WP failed, assume Write Enabled
[ 5.177015] sd 0:0:0:0: [sda] Asking for cache data failed
[ 5.185504] sd 0:0:0:0: [sda] Assuming drive cache: write through
[ 5.232396] sd 0:0:0:0: [sda] Attached SCSI disk
[ 6.453816] bcm2708-i2s bcm2708-i2s.0: Failed to create debugfs directory
[ 10.936173] EXT4-fs (mmcblk0p2): re-mounted. Opts: (null)
[ 11.561156] EXT4-fs (mmcblk0p2): re-mounted. Opts: (null)
[ 17.880623] EXT4-fs (sda1): mounted filesystem with ordered data mode. Opts: (null)
[ 20.349019] smsc95xx 1-1.1:1.0 eth0: hardware isn't capable of remote wakeup
[ 21.880994] smsc95xx 1-1.1:1.0 eth0: link up, 100Mbps, full-duplex, lpa 0xCDE1
[ 26.334154] Adding 102396k swap on /var/swap. Priority:-1 extents:1 across:102396k SSFS
[ 1825.964304] bcm2708_fb_blank(1) returns=1 p[1]=0x80000000