MyComputingArt (circa 1993)

I have a dual boot configuration with Windows XP booting from a EIDE disk and Ubuntu booting from a SATA disk, so I entered Ubuntu, successfully; /dev/hda1 (the Windows partition) was not mounted while /dev/hda5 and /dev/hda6 were; attempting to mount it resulted in

Special device /dev/hda1 does not exist

At reboot I started Windows XP Recovery Console from the Windows CD and tried CHKDSK.EXE, and this was the outcome:

The volume appears to contain one or more unrecoverable problems

I booted again linux to launch fsck and see it fail:

Logical sector size is zero.

Then I found the solution in ubuntu forum:

root@am2:/home/z24# dd if=/dev/hda1 of=/defmedia/bkup_fat32_hda1.img bs=512 count=2048000 conv=noerror,sync
2048000+0 records in
2048000+0 records out
1048576000 bytes (1.0 GB) copied, 43.61 seconds, 24.0 MB/s

root@am2:/home/z24# dd if=/defmedia/bkup_fat32_hda1.img of=/home/z24/sector6.bin bs=512 count=1 skip=6 conv=noerror,sync
1+0 records in
1+0 records out
512 bytes (512 B) copied, 0.011544 seconds, 44.4 kB/s

root@am2:/home/z24# dd if=/home/z24/sector6.bin of=/dev/hda1 bs=512 count=1 conv=noerror,sync,notrunc
1+0 records in
1+0 records out
512 bytes (512 B) copied, 0.030644 seconds, 16.7 kB/s

Explanation:

the first dd makes a backup of the first gigabyte of the Windows partition: I copied 1 GB only because I didn't have enough space on a ext2fs to backup all the 28 GB of /dev/hda1.
the second dd extracts the sixth sector to a temporary file: as reported by Microsoft KB247575, "The backup FAT32 boot sector is located at sector 6 of the logical drive".
the third dd copies the extracted sector 6 to sector 0 of /dev/hda1.

In the original post the partition that was just backupped with dd was also checked with losetup and mount. Thanks a lot to the ubuntuforums user Onlymee for his post!

Update 13.09.2008

The same problem happened again today and gave me the opportunity to complete the series of error messages :)
The first, at boot time, was the same:

grub: 13 : Invalid or unsupported executable format

Mounting the partition (mount -t vfat /dev/sda1 /mnt):

mount: wrong fs type, bad option, bad superblock on /dev/sda1, missing codepage or other error

dmesg | grep sda1

VFS: Can't find a valid FAT filesystem on dev sda1

But fdisk -l /dev/sda shows the partition table.
fsck.vfat /dev/sda1 (executed from Ubuntu 8.04 alternate cd)

Cluster size is zero

The solution was exactly the same: copy the sixth sector back to the first. And voilà, it booted.
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Sun, 17 Jun 2007

Mounting a second fan on the back of the case (Antec SLK3000B)
With the summer approaching, I am making some experiments trying to cool my pc as much as possible while keeping it quiet. Now, airflow in the case is made by 2 fans: the intake fan, a Papst 4412 F/2GLL, pulls air inside the case from the front, the exhaust fan, a Antec Tricool coming with the SLK3000B, pushes air out to the back; in addition, the psu fan pulls air from the top of the motherboard through the psu to the back.
Since I bought a second Papst 4412 F/2GLL, I tried positioning this fan in different locations to see which one conributes the best to the cooling. One of these is the back of the case, in the bottom, where there would be additional cards: it pushes air out of the case through the back slots.

See full post ...

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Tue, 12 Jun 2007

Hard disk suspension in an Antec SLK3000B
The main problem of the Antec SLK3000B case is it converts hard disk vibrations to noise, and this is the most annoying noise coming from my pc when the fans are set at the lowest speed. In the SLK3000B the hard disks lay in a cage with grommets that are supposed to dampen the vibrations of the 7200 and more rpm hard disks.
The trend spreading amongst silencing modders is to suspend the hard disks in the air to avoid contact between the case and the hard disks.

See full post ...

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