Re: Best suiting OS

Scott Carey wrote:
> On 10/3/09 7:35 PM, "Karl Denninger" <karl(at)denninger(dot)net> wrote:
>
>
>> I am a particular fan of FreeBSD, and in some benchmarking I did between it
>> and CentOS FreeBSD 7.x literally wiped the floor with the CentOS release I
>> tried on IDENTICAL hardware.
>> I also like the 3ware raid coprocessors - they work well, are fast, and I've
>> had zero trouble with them.
>>
>> -- Karl
>>
>
> With CentOS 5.x, I have to do quite a bit of tuning to get it to perform
> well. I often get almost 2x the performance after tuning.
>
> For I/O --
> Deadline scheduler + reasonably large block device read-ahead + XFS
> configured with large 'allocsize' settings (8MB to 80MB) make a huge
> difference.
>
> Furthermore, the 3ware 35xx and 36xx (I think) I tried performed
> particularly badly out of the box without tuning on CentOS.
>
> So, Identical hardware or not, both have to be tuned well to really compare
> anyway.
>
> However, I have certainly seen some inefficiencies with Linux and large use
> of shared memory -- and I wouldn't be surprised if these problems don't
> exist on FreeBSD or OpenSolaris.
>
I don't run the 3x series 3ware boards. If I recall correctly they're
not true coprocessor boards and rely on the host CPU. Those are always
going to be a lose compared to a true coprocessor with dedicated cache
memory on the card.

The 9xxx series boards are, and are extremely fast (make sure you
install the battery backup or run on a UPS, set the appropriate flags,
and take your chances - writeback caching makes a HUGE difference.)

Other than pinning shared memory on FreeBSD (and increasing a couple of
boot-time tunables to permit large enough shared segments and semaphore
lists) little is required to get excellent performance.

The LSI cards that DELL, Intel and a few others have used (these appear
to be deprecated now as it looks like LSI bought 3ware) also work well
but their user interface is somewhat of a pain in the butt compared to
3Ware's.

-- Karl