Quick question... on use with "Ram Drives" or FOBs...

["Michael J. Segel" <ms...@segel.com>]

Hi,

Quick question...

Has anyone tried using Derby/Cloudscape with the data being written to one of 
those 512MB FOBs instead of a hard drive?

Got in to a discussion over a beer last night regarding "in memory" databases 
vs solid state drives vs those FOBs that now have over a GB of storage.

Trying to see if we can improve performance by a simple hardware change....

Thoughts?

-- 
Michael Segel
Principal
MSCC
(312) 952-8175

Re: Quick question... on use with "Ram Drives" or FOBs...

["Michael J. Segel" <ms...@segel.com>]

On Wednesday 17 August 2005 10:57, David Van Couvering wrote:
> BTW, what kind of application do you have that doesn't require the data
> to be persistent over a memory failure?
>
Thats a good question, there are several scenarios that this could be applied.
(I'll give you an example shortly...)

The purpose of the discussion was to see if there were some simple hardware 
tricks that could be used to improve performance.

Considering the order (fastest to slowest):
Ram Drives would be the fastest storage/retrival system.
Bubble Memory / Flash Memory/ Memory sticks would be second.
10K RPM drives (High end scsi) would be the third,
7200 RPM drives (SATA, SCSI, IDE) would be the fourth.

Ram drives are the fastest but have the greatest risk due to their need to 
constant power.

The real question is that if we keep the database schema, transaction type, 
and transaction volume constant across these different types of media, we 
should see a performance difference. (Also trying to keep the amount of 
memory and other system stuff as constant as possible too.)


There are a couple of applications where you would want to put a portion of 
your database on high speed "persistent memory" storage. (You can see this in 
financial applications for example, or in some telemetry systems where you 
have high capture rates of important information.) There are a couple of ways 
to achieve this, however, the idea of using a flash card or memory stick does 
offer some interesting alternatives that are at a potential price point. 

Using a financial system example...
You want to create a system which captures trades in real time and then 
performs some calculations on the trade and some caputred data.

You can do this in memory since you're splitting the incoming feed to your 
persistant storage unit. If your trading system fails, you restart the real 
time feed and then reload the persistant data and resume trading. (In that 
order.)

With respect to a FOB or memory stick, there are some interesting applications 
too.
-- 
Michael Segel
Principal
MSCC
(312) 952-8175

Re: Quick question... on use with "Ram Drives" or FOBs...

[Mike Matrigali <mi...@sbcglobal.net>]

I am not exactly sure of the terminology, but some sort of RAM drive for
the log device makes the entire autocommit log sync issue go away - and
since we garbage collect the log then we don't need that big of a device.

We
have a machine here which has a relatively small memory backed ram cache
in front of a real hard drive and it does the trick also, it is just a
feature of the controller - we didn't even know it was there until our
autocommit performance numbers looked an order of magnitude or more better.

It does not
have to be very big as it just needs to cache it in a safe manner until
a big write can take it all to the real disk - I think it is only 512 bytes.

In memory database will have other benefits, but just putting the derby
db on an memory disk may give an application all the performance it needs.

Michael J. Segel wrote:

> Hi,
> 
> Quick question...
> 
> Has anyone tried using Derby/Cloudscape with the data being written to one of 
> those 512MB FOBs instead of a hard drive?
> 
> Got in to a discussion over a beer last night regarding "in memory" databases 
> vs solid state drives vs those FOBs that now have over a GB of storage.
> 
> Trying to see if we can improve performance by a simple hardware change....
> 
> Thoughts?
> 

Re: Quick question... on use with "Ram Drives" or FOBs...

[David Van Couvering <Da...@Sun.COM>]

I would suggest you just try it -- if it supports all the filesystem 
semantics and looks and tastes like a file system, it should "just work."

David

Michael J. Segel wrote:

>Hi,
>
>Quick question...
>
>Has anyone tried using Derby/Cloudscape with the data being written to one of 
>those 512MB FOBs instead of a hard drive?
>
>Got in to a discussion over a beer last night regarding "in memory" databases 
>vs solid state drives vs those FOBs that now have over a GB of storage.
>
>Trying to see if we can improve performance by a simple hardware change....
>
>Thoughts?
>
>  
>

Re: Quick question... on use with "Ram Drives" or FOBs...

[David Van Couvering <Da...@Sun.COM>]

BTW, what kind of application do you have that doesn't require the data 
to be persistent over a memory failure?

Michael J. Segel wrote:

>Hi,
>
>Quick question...
>
>Has anyone tried using Derby/Cloudscape with the data being written to one of 
>those 512MB FOBs instead of a hard drive?
>
>Got in to a discussion over a beer last night regarding "in memory" databases 
>vs solid state drives vs those FOBs that now have over a GB of storage.
>
>Trying to see if we can improve performance by a simple hardware change....
>
>Thoughts?
>
>  
>

Re: Quick question... on use with "Ram Drives" or FOBs...

[Piet Blok <pb...@wanadoo.nl>]

Hi Michael,

Yes, I tried to setup a (small) derby database on a memory stick (256 MB), 
and as expected this works fine.

I also installed the .jar file of an application (with embedded derby 
driver) on the stick.

I even installed a (windows) JRE on the memory stick and created a .bat file 
to start java explicitly from its JRE path.

Thus I was able to to run my application, including database, on any windows 
machine I encountered, with or without java installed, provided it had a 
working USB port.

Reasoning for this exercise was a prototype of an intelligent device that 
can be easily carried around and plugged in anywhere.

Startup performance is bad, but for the rest it works OK. (I am told by 
someone more familiar with memory sticks that performance is higly 
influenced by the machine's installed USB support, but I cannot comment on 
that).

(I assume FOBs refers to memory sticks?)

Piet Blok

----- Original Message ----- 
From: "Michael J. Segel" <ms...@segel.com>
To: "Derby Discussion" <de...@db.apache.org>
Sent: Wednesday, August 17, 2005 1:54 AM
Subject: Quick question... on use with "Ram Drives" or FOBs...


> Hi,
>
> Quick question...
>
> Has anyone tried using Derby/Cloudscape with the data being written to one 
> of
> those 512MB FOBs instead of a hard drive?
>
> Got in to a discussion over a beer last night regarding "in memory" 
> databases
> vs solid state drives vs those FOBs that now have over a GB of storage.
>
> Trying to see if we can improve performance by a simple hardware 
> change....
>
> Thoughts?
>
> -- 
> Michael Segel
> Principal
> MSCC
> (312) 952-8175
>
>