[Bizgres-general] Sizing a server to host Bizgres...

[Steve Atkins]

On May 2, 2006, at 9:39 AM, Jim C. Nasby wrote:

> On Tue, May 02, 2006 at 08:05:30AM -0700, Luke Lonergan wrote:
>> Hannu,
>>
>> On 5/2/06 5:47 AM, "Hannu Krosing" <hannu at skype.net> wrote:
>>
>>> or maybe DMA is not enabled, what does "hdparm /dev/hda" say ?
>>>
>>> modern IDE disk get usually something in between 40 and 80MB/swc
>>
>> This is absolutely the problem - I never understood why RedHat  
>> kept the
>> default I/O settings for ATA so pathetically bad.
>>
>> You need to go to /etc/sysconfig and edit the file "harddisks" there.
>> Uncomment all of the commented settings and add "-u1" to the  
>> EXTRA_PARAMS=
>> line.
>>
>> To have these settings take effect before reboot, issue this command:
>>   hdparm /dev/had -d1 -c1 -m16 -u1
>>
>> Then do a "hdparm -tT /dev/hda" to benchmark it.
>
> I hope none of that is enabling the drive's write cache...

No. (I was interested enough to go read the hdparm manpage, so I
may as well share.)

-d1 - use dma
-c1 - use 32 bit IDE support
-m16 - burst transfer multiple sectors
-u1 - service interrupts during disk interrupt processing
-t and -T - time cache and device reads.

Cheers,
   Steve