write cache and read look-ahead in ffs

write cache and read look-ahead in ffs

Post by Igor Sobrad » Mon, 28 Jul 2003 03:24:49

This is a question that should be easy to answer, but not so obvious.
From [1] it seems that disabling the hard disks write cache is a
requirement to increase the fast filesystem reliability in NetBSD.  I asked
some related questions in the past; now I am interested in know:

   1. if we should disable the write cache in hard disk drives that
      support this feature; and,
   2. if we should disable the read look-ahead option too.

(I believe that the answer to the first question will be "yes", but
the answer to the second one will be "no" or "it does not matters".)
Any advice will be highly appreciated.


[1]  Gregory R. Ganger, Marshall Kirk McKusick, Craig A. N. Soules,
     Yale N. Patt.  Soft updates: a solution to the metadata update problem
     in file systems, ACM Transactions on Computer Systems 18(2), May 2000.



1. Partitioning a Maxtor 1.26 GIG Drive with VLB Read-Ahead Cache IDE Controler


You are going to love this quesion.

My brother has a Vesa Local Bus IDE-Control Card with Read Ahead Cache (2 1x9 1
meg simms that do local caching to accelerate my IDE Drives).

It works fine for his 340 Western Digital Drive.  Well, we just bought a 1260AT
Maxtor (1.26 Gig with Logical Block Addressing (LBA)).  I boot up linux (either
with the Boot and Root floppies making my new drive the master, or booting the
linux directly from his Western Digital drive, making hte new Maxtor a slave),
and I keep getting bad partition errors from the startup.  Well, I ignore those
errors and am able to partition the drive.  Then, I try using the mke2fs
command to format my new linux partition.  I keep getting these
ide_busy_status:  IDE_RESET messages.  I don't think it can access the
partition b/c of the combination of the Specialized IDE Card and the Maxtor's

I have the same exact drive, except I have a normal 16 bit IDE Control Card and
it works fine.

Any help would be very helpful.


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