terrible HD I/O speed on laptops where hdb is the CD (inspiron 8200)

[Peter Teuben]

On [Fri Dec 15 23:45], Peter Teuben wrote:
> This is a very old topic about which I've reported before and has
> some old entries in redhat/fedora's bugzilla. But the basic problem is
> that in order for desktops to "automatically" detect that a CD has
> been added/removed, it has to poll /dev/hdb, but poor little /dev/hda
> is then interrupted, at least on a Dell 8200 this causes the HD
> performance to go down by about a factor 2-4.
> 
> hdparm then reports erratic I/O (5-10 MB/s, where the drive will do a
> consistent 38 MB/sec in my case in single user mode).
> 
> In fedora5 and 6 this is now done by hald-addon-storage, which appears
> in the process table as polling hdb.   I suspect it's a Dell 8200 problem
> (hardware related), though i have an 8600 to play with, and a thinkpad T40
> i can try as well.    It might also be the settings of the HD, i tried
> playing with the hdparm options, but nothing will bring it back to a
> consistent level, other than killing the polling task.   As said,this is
> a very old topic.
> 
> I'd love to hear any other/more reports on this issue.  Eventually i'll 
> file a bugzilla on this of course.

That was old bug 138148, but it was re-entered in FC6 bugzilla:
https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=213995

A reasonable solution is to insert a CD/DVD and keep it in the drive,
it will bring the disk I/O up to a steady 26 MB/sec, however, if you
stop the haldaemon, mine will go up to a much more respectable 38 MB/sec.

- peter