One should ALWAYS do a sync after a dd. I learned this the hard way...
On 6/22/25 10:34 PM, Jeffrey Walton wrote:
On Sun, Jun 22, 2025 at 10:01 PM Tim via users <users@lists.fedoraproject.org> wrote:Is it no-longer possible to use dd to write an install ISO to a flashdrive, or is there something wrong with the ISO (which passes the checksum tests)? If I do this command: [root@rocky fedora42]# dd if=Fedora-Server-dvd-x86_64-42-1.1.iso of=/dev/sdb status=progress 2923241984 bytes (2.9 GB) copied, 1204.794829 s, 2.4 MB/s 5714688+0 records in 5714688+0 records out 2925920256 bytes (2.9 GB) copied, 1212.03 s, 2.4 MB/s Marvel at the blistering write speed!! But ignore that for this problem. I see this in the system log after it finishes: Jun 23 11:14:23 rocky kernel: GPT:Primary header thinks Alt. header is not at the end of the disk. Jun 23 11:14:23 rocky kernel: GPT:5714027 != 30310399 Jun 23 11:14:23 rocky kernel: GPT:Alternate GPT header not at the end of the disk. Jun 23 11:14:23 rocky kernel: GPT:5714027 != 30310399 Jun 23 11:14:23 rocky kernel: GPT: Use GNU Parted to correct GPT errors. Jun 23 11:14:23 rocky kernel: sdb: sdb1 sdb2 And if I unplug it then replug it: Jun 23 11:22:59 rocky kernel: usb 1-11: USB disconnect, device number 8 Jun 23 11:23:08 rocky kernel: usb 1-11: new high-speed USB device number 27 using xhci_hcd Jun 23 11:23:08 rocky kernel: usb 1-11: New USB device found, idVendor=18a5, idProduct=0304, bcdDevice= 1.12 Jun 23 11:23:08 rocky kernel: usb 1-11: New USB device strings: Mfr=1, Product=2, SerialNumber=3 Jun 23 11:23:08 rocky kernel: usb 1-11: SerialNumber: 13120286006070 Jun 23 11:23:08 rocky kernel: usb-storage 1-11:1.0: USB Mass Storage device detected Jun 23 11:23:08 rocky kernel: scsi host18: usb-storage 1-11:1.0 Jun 23 11:23:08 rocky mtp-probe: checking bus 1, device 27: "/sys/devices/pci0000:00/0000:00:14.0/usb1/1-11" Jun 23 11:23:08 rocky mtp-probe: bus: 1, device: 27 was not an MTP device Jun 23 11:23:09 rocky kernel: scsi 18:0:0:0: Direct-Access Verbatim 8.07 PQ: 0 ANSI: 4 Jun 23 11:23:09 rocky kernel: sd 18:0:0:0: Attached scsi generic sg2 type 0 Jun 23 11:23:09 rocky kernel: sd 18:0:0:0: [sdb] 30310400 512-byte logical blocks: (15.5 GB/14.4 GiB) Jun 23 11:23:09 rocky kernel: sd 18:0:0:0: [sdb] Write Protect is off Jun 23 11:23:09 rocky kernel: sd 18:0:0:0: [sdb] Write cache: disabled, read cache: enabled, doesn't support DPO or FUA Jun 23 11:23:09 rocky kernel: GPT:Primary header thinks Alt. header is not at the end of the disk. Jun 23 11:23:09 rocky kernel: GPT:5714027 != 30310399 Jun 23 11:23:09 rocky kernel: GPT:Alternate GPT header not at the end of the disk. Jun 23 11:23:09 rocky kernel: GPT:5714027 != 30310399 Jun 23 11:23:09 rocky kernel: GPT: Use GNU Parted to correct GPT errors. Jun 23 11:23:09 rocky kernel: sdb: sdb1 sdb2 Jun 23 11:23:09 rocky kernel: sd 18:0:0:0: [sdb] Attached SCSI removable disk And it can't be mounted.I used to encounter this on occasion when I refreshed my desktop to one with 64GB of RAM. My take was, the cache manager could hold a lot more in RAM before [asynchronously] flushing the write to disk. Try adding a `sync` to the command line: dd if=Fedora-Server-dvd-x86_64-42-1.1.iso of=/dev/sdb \ status=progress && sync /dev/sdb Otherwise, the media used for /dev/sdb may be going bad. But I usually only encounter this on SDcards, and not USB drives. Jeff
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