ATA disks and DB

[Xose Vazquez Perez]

Frank Warnke wrote:

> Could you elaborate on why "IDE disk/controllers and journal fs are not
> recommended for DB usage"?  Does "DB" mean database?  Does this blanket
> statement cover ATA RAID controllers as well?  Is this a performance
> issue or a data loss issue? 

yes.
yes, DB = data base.
yes, it covers ATA RAID controllers.
it's a data loss issue.

main problems:
ATA disks _manufacturers_ enable write-back-caching
and
ATA disks allow to reorder the operations in write-back-cache

There a lot of literature about that:
http://sr5tech.com/write_back_cache_experiments.htm
http://sr5tech.com/download/ATA_RAID5_Whitepaper.pdf
http://archives.postgresql.org/pgsql-admin/2000-12/msg00094.php
http://redhat.com/archives/fedora-test-list/2003-November/msg01447.html
http://redhat.com/archives/fedora-test-list/2003-December/msg00001.html
http://marc.theaimsgroup.com/?t=104991701200010&r=1&w=2
http://marc.theaimsgroup.com/?t=107014526000001&r=2&w=2
http://marc.theaimsgroup.com/?l=linux-kernel&m=106745860511194&w=2

> I also have over 40 servers in the field using either Dell(LSI) or 3ware
> PATA/SATA hardware RAID controllers (RAID5) running databases on
> ReiserFS and EXT3 filesystems.  Many have seen close to two years of
> service and they have been problem free.  Our customers are very pleased
> with the performance of the database access.

if you did not have any problem, it doesn't guarantee that it can not
happen

> People, including myself, come here to learn and when we can, add our
> experiences.  Please be careful with your opinions, there are a lot of
> people viewing this list because they assume you have the answers based
> on experience.  It would help a viewer of this thread to see a reference
> or two to substantiate your claim.  If I have done a customer a
> disservice in the configuration of their servers, I want to remedy it
> immediately.

Those are no personal opinions, they are real facts.
My opinions are mine, if you don't like them you are free to delete the
e-mail and forget it :-)