Re: read buffer size AIX 4.2 / Oracle 7.3.x

In article <34E3D6C4.8D399CE3_at_cse.uta.edu>, Kevin Gee <geek_at_cse.uta.edu> wrote:
>William Tierney wrote:
>>
>> Sorry .. not sure if I'm asking this correctly..
>>
>> As part of Oracle install / perf + tuning regarding
>> multi_block_read ..I'm suppose to know
>> the size of the 'read buffer' of the OS. The book
>> says for HPUX is is 64k ..but nothing for AIX.
>>
>> Someone told me that almost all unix is at 64k..
>>
>> Does anyone know what the 'read buffer' size is
>> for AIX?
>
>
>4K.

I am trying to find out the same information for Sun Solaris on an E5000 with Sun's Storage Array. When I ask the sysadmins or hardware vendor, they usually confuse the "optimal read/buffer" size with either the OS file buffer size or the disk cache size. I am looking for a the answer to

                                 (db_block_size * multi_block_read_count)
optimal_stripe_width =   ------------------------------------------------
                                        "optimal read/buffer size"             

I am not quite sure what the denominator really is, but I know it is not the OS file buffer size (mine are all raw devices) and I really don't think it is the size of the disk's internal cache since that would need to absurd answers in light of recommended values for the Oracle variables. For example:

                 8k * 16
    OSW = ------------ = 0.25 disks/stripe!!!!!!  (or 0.5 or 1.0 ???????)
                  512k

I suspect this is a function of the hardware only, but not simply the disk internal cache size.

-OraSaurus Received on Sat Feb 14 1998 - 00:00:00 CST