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Filesystem in memory?

 
Diego Pavón
Advisor

Filesystem in memory?

Hi.

Anybody know if it is possible to be one filesystem in memory?. Can I have one filesystem working in RAM?. I need to be one filesystem with the best performance, and always the memory has it.
Anybody know any about this?

Thank in advance.
6 REPLIES 6
James R. Ferguson
Acclaimed Contributor

Re: Filesystem in memory?

Hi:

The idea behind buffer cache is to increase the performance of a filesystem by keeping recently used buffers in memory. 'dbc_min_pct' and 'dbc_max_pct', control the lower and upper limit allocated as a percentage of total system memory.

For VxFS filesystems some additional performance may also be achieved by increasing parameters dealing specifically with this type of filesystem. For example increasing 'vxfs_ncsize' may heighten the liklehood of finding a directory and its contents in a name cache as opposed to doing a disk I/O.

As always, emperical evidence is the best guide to how well a parameter change helps or hurts performance.

Regards!

...JRF...
harry d brown jr
Honored Contributor

Re: Filesystem in memory?

Diego,

Are you talking about something like a "ramdisk" ??

I've used them in linux, but I haven't in HPux, and I don't think they are "supported".

live free or die
harry

Live Free or Die
Leif Halvarsson_2
Honored Contributor

Re: Filesystem in memory?

Hi,
Perhaps this can interest you:
http://www.bitmicro.com/products_edsw.html
Wodisch
Honored Contributor

Re: Filesystem in memory?

Rajasekhar Raman
Frequent Advisor

Re: Filesystem in memory?


We have been using RAM disks for a few years now and have had excellent performance. They outperform regular disks (even FC-AL disks) by an order of magnitude cos their response time is around 25 microseconds even at heavy loads. Also, since there are no moving parts in a RAM disk, they are very reliable, but ofcourse you will have to PAY for them!!! around $4000 per Gigabyte.

If you have a database application that you trying to set the filesystem up for, I would suggest increase the memory and shared memory parameters on the machine and the data cache parameter on the database, so that most of the data on the DB is loaded onto RAM. (Thats how Sybase works, not sure about ORacle)

-Shekar
harry d brown jr
Honored Contributor

Re: Filesystem in memory?

Diego,

A little interaction here would help?

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harry
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