Problems even with 512 block size MOs

Problems even with 512 block size MOs

[Uwe Bonnes]

Hallo

recent 2.4 kernels have incredible bad performance for me when handling MO
drives. Going back 2.2 shows better performance.

This is my setup:
SCSI subsystem driver Revision: 1.00
ncr53c8xx: at PCI bus 0, device 15, function 0
ncr53c8xx: 53c810 detected 
ncr53c810-0: rev 0x2 on pci bus 0 device 15 function 0 irq 16
ncr53c810-0: ID 7, Fast-10, Parity Checking
scsi0 : ncr53c8xx-3.4.3-20010212
  Vendor: FUJITSU   Model: M2513A            Rev: 1500
  Type:   Optical Device                     ANSI SCSI revision: 02
  Vendor: PIONEER   Model: DVD-ROM DVD-303   Rev: 1.10
  Type:   CD-ROM                             ANSI SCSI revision: 02
Detected scsi removable disk sda at scsi0, channel 0, id 0, lun 0
ncr53c810-0-<0,*>: FAST-10 SCSI 10.0 MB/s (100 ns, offset 8)
SCSI device sda: 248826 512-byte hdwr sectors (127 MB)
sda: Write Protect is off
 sda: unknown partition table

on a non-overclocked Dual celeron BP6 machine with 256MByte RAM

hertz:~> uname -a
Linux hertz 2.4.4-SMP #2 SMP Wed May 2 17:47:22 MEST 2001 i686 unknown
(recent kernel from ftp.suse.com/people/mantel/next) 

Copying a 6.5 MByte file with cp returns nearly immediately on the
commandline, but umount nearly takes forever. Maximum rate detected by
xosview during umount was about 30 kByte.

I have similar behaviour on another machine and with different disk. However
I don't get any "dmesg" output despite the "CONFIG_SCSI_LOGGING=y" option on
both machines.

Are all my MO disks rotten? Are the MO drives broken? Are my SCSI adapters
broken? Or is there a bug in the SCSI layer?

Bye

-- 
Uwe Bonnes                bon@elektron.ikp.physik.tu-darmstadt.de

Institut fuer Kernphysik  Schlossgartenstrasse 9  64289 Darmstadt
--------- Tel. 06151 162516 -------- Fax. 06151 164321 ----------

Re: Problems even with 512 block size MOs

[Alan Cox]

> Copying a 6.5 MByte file with cp returns nearly immediately on the
> commandline, but umount nearly takes forever. Maximum rate detected by
> xosview during umount was about 30 kByte.
> 
> I have similar behaviour on another machine and with different disk. However
> I don't get any "dmesg" output despite the "CONFIG_SCSI_LOGGING=y" option on
> both machines.

That sounds like it isnt queueing multiple commands at a time. M/O has
an erase/write sequence so you want to queue large blocks otherwise its two
rotations per I/O

> Are all my MO disks rotten? Are the MO drives broken? Are my SCSI adapters
> broken? Or is there a bug in the SCSI layer?

SCSI layer or scsi driver I suspect.

Re: Problems even with 512 block size MOs

[Giuliano Pochini]

> recent 2.4 kernels have incredible bad performance for me when handling MO
> drives. Going back 2.2 shows better performance.

> Copying a 6.5 MByte file with cp returns nearly immediately on the
> commandline, but umount nearly takes forever. Maximum rate detected by
> xosview during umount was about 30 kByte.

I have this one:

  Vendor: FUJITSU   Model: MCD3130SS         Rev: 0020

and it works very well with 2.4. 2.2 kernel perform really badly because of
the famous merging problem.

> Are all my MO disks rotten? Are the MO drives broken? Are my SCSI adapters
> broken? Or is there a bug in the SCSI layer?

No probs here. I have an Adaptec SCSI card.

Bye.