Hello:
To an old Acer Veriton 7500 I have transferred master and slave HDs (as well as a Realtek network card, a scsi card, and a usb2 card) from a died old machine, Debian Linux squeeze i386. Everything works, except problems with the CDs, as noticed on boot. Check:

francesco@deb32:~$ dmesg | grep -i hdc
[ 3.472184] hdc: CD-ROM 52X/AKH, ATAPI CD/DVD-ROM drive
[ 3.808070] hdc: host max PIO4 wanted PIO255(auto-tune) selected PIO4
[ 3.808175] hdc: bad DMA info in identify block
[ 3.808233] hdc: host max PIO4 wanted PIO255(auto-tune) selected PIO4
[ 4.033058] ide-cd: hdc: ATAPI 52X CD-ROM drive, 192kB Cache
[ 1006.070740] ide-cd: hdc: weird block size 2352
[ 1006.070746] ide-cd: hdc: default to 2kb block size
[ 1006.230322] ide-cd: hdc: weird block size 2352
[ 1006.230328] ide-cd: hdc: default to 2kb block size
[ 1006.398620] ide-cd: hdc: weird block size 2352
[ 1006.398627] ide-cd: hdc: default to 2kb block size
[ 1065.222309] hdc: request sense failure: status=0x51 { DriveReady SeekComplete Error }
[ 1065.222322] hdc: request sense failure: error=0xb4 { AbortedCommand LastFailedSense=0x0b }
[ 1065.222330] hdc: possibly failed opcode: 0xa0
francesco@deb32:~$

I would appreciate suggestions from where to start repair, from verifying cables to deeper checks.

Thanks
francesco

Turn off dma on that antique cd drive. It wants PIO 4 which is a slow trot, compared with the galloping dma
man hdparm

Thanks. As the wrtiter was even older and did not deal with DVD, I replaced both with

[ 3.552185] hdc: HL-DT-STDVD-RAM GH22NP20, ATAPI CD/DVD-ROM drive
[ 3.888065] hdc: host max PIO4 wanted PIO255(auto-tune) selected PIO4
[ 3.888232] hdc: host side 80-wire cable detection failed, limiting max speed to UDMA33
[ 3.888236] hdc: UDMA/33 mode selected
[ 4.000087] ide-cd: hdc: ATAPI 48X DVD-ROM DVD-R/RAM CD-R/RW drive, 2048kB Ca

As far as I can understand, the limit to PIO4 is imposed by the IDE connection. At any event, this desktop is amply enough to analyze data from the mainframe used for chemical computations. As the bill for electrons to the desktop is to me, my interest is to keep the bill as low as possible.

francesco