Raid configurations

"Bernd Felsche" wrote in message

> "S W" wrote:
>
>>How important is RAID 10 on a Progress 9.1E installation?
>
> As important as for other RDBMS.
>
>>We have an installation where everything is on RAID 1.
>
> RAID 1 (mirroring) delivers most of the performance boost as data
> are duplicated over drives and can be retrieved from any of the
> mirrored drives. Most IO in applications is to read data. Writing on
> RAID 1 is "slower" unless it's via multiple system channels.
>
> RAID 0 (striping) provides a performance boost when large amounts of
> data need to be retrieved by distributing the reading and writing of
> data over multiple drives.
>
>>Would you expect any problems with this config? Would moving the DB onto
>>RAID10 improve things greatly? The reason I ask is because the application
>>is slow.
>
> You won't see ANY improvement unless the application is slow because
> of an IO bottleneck.
>
> There's a myriad of reasons why applications run slowly. Most of the
> time, it's down to either application design or implementation; i.e.
> the application software.
>
> If there is really an IO bottleneck, then going from RAID 1 to RAID
> 10 will at best produce marginal results.
>
> You need to do a detailed, device and file-level IO analysis to
> identify the particular bottleneck and add bandwidth at that point.
> Without an analysis, you'll be throwing a lot of time and money at
> the problem, trying to fix it, with only a random chance that it
> will actually fix it; and an even better chance that it will make
> things worse.
>
> RAID is not a panacea. RAID is more of a placebo.
> --
> /"\ Bernd Felsche - Innovative Reckoning, Perth, Western Australia
> \ / ASCII ribbon campaign | Second to agriculture, humbug is the
> X against HTML mail | biggest industry of our age.
> / \ and postings | -- Alfred Nobel

Hi Bernd
Thanks for your help and valuable info.
Since posting the original question, we have done detailed IO analysis using
different "models" or scenarios of data server uses, and found that the
system is actually OK at reading data, but maybe a little slow at writing
it. I now agree that RAID 10 would not make a huge difference. But its still
slow. We're having a Progress analyst doing a system health check in the
next few days, which hopefully will throw more light onto things.
Regards,
SW
 >> Stay informed about: Raid configurations 

"SW" wrote:
>"Bernd Felsche" wrote:
>> "S W" wrote:

>>>How important is RAID 10 on a Progress 9.1E installation?

<snip>

>> You need to do a detailed, device and file-level IO analysis to
>> identify the particular bottleneck and add bandwidth at that point.
>> Without an analysis, you'll be throwing a lot of time and money at
>> the problem, trying to fix it, with only a random chance that it
>> will actually fix it; and an even better chance that it will make
>> things worse.

>> RAID is not a panacea. RAID is more of a placebo.

>Since posting the original question, we have done detailed IO
>analysis using different "models" or scenarios of data server uses,
>and found that the system is actually OK at reading data, but maybe
>a little slow at writing it. I now agree that RAID 10 would not
>make a huge difference. But its still slow. We're having a Progress
>analyst doing a system health check in the next few days, which
>hopefully will throw more light onto things.

How did you go?

Depending on where you are writing, more spindles and spreading the
data and meta-data can make a big difference.

Non-volatile RAM drives (Flash) now seem to be getting there; with
durability better than that of rotating media. Data density isn't
quite so good, nor purchase cost.

Progress RDBMS systems would benefit most dramatically by putting
the BI on "solid-state disk". If your databases a small enough, you
can whack the whole lot onto one card. (Keep the HDD for AI and
backups.)

Fusion-IO are about to start shipping (finger crossed) PCI cards
with sustained write speeds of 600 megabytes per second (100,000+ IO
per second). There is no seek latency. It is about 100 times faster
than a 10,000 rpm HDD. The card plugs into a PCI-E slot, bypassing
the HDD hardware.

<http://www.dvnation.com/Fusion-IO-IODrive-SSD-Solid-State-Disk-Drive-Review.html>

It looks very promising. Revolutionary and paradigm-shifting.

But Santa didn't leave one for me at Christmas.

2009 is likely to see the first NUMA-extended servers on the market;
with slots for such flash-based non-volative RAM as well as normal
DRAM. JEDEC are discussing standards. Hope they won't be slowed too
much by the financial crunch.
--
/"\ Bernd Felsche - Innovative Reckoning, Perth, Western Australia
\ / ASCII ribbon campaign | Second to agriculture, humbug is the
X against HTML mail | biggest industry of our age.
/ \ and postings | -- Alfred Nobel
 >> Stay informed about: Raid configurations