Installation query

[khilari]

Hi guys, i wanted to know that when you are in the filesystem installation phase of installation. Now, u get the option root swap and it is usually recommended to have twice the physical memory. Y is that. Secondly, in new installations can we just do a default filesystem install and just increase the size later on, before the application is mounted.
Thanks

[Ivan Krastev]

You can easily change swap/dump after installation if you missed that during initial setup.

See "Managing Swap and Dump" doc - http://docs.hp.com/en/B2355-90950/ch06s03.html


regards,
ivan

[Srimalik]

I think you are asking about the swap partition. swap space is a space on hard drive which is used to store some part(pages) of main memory when there is not enough space in the RAM to load new pages.

say u are running x number of processes on a system and the RAM is 99.99% full. Now you start a new process, the OS tries to load this process for execution into the RAM, as there is not enough space some pages of the older process are saved on a reserved area on the hardrive, this reserved area is called swap space.

In short swap is an extention to RAM.

for more information please google about about Virtual memory, paging, page faults, and related topics

[Court Campbell]

>Secondly, in new installations can we just do a default file system install and just increase the size later on, before the application is mounted.

Yes and no. That is my favorite answer. Yes you can resize lvols after installation. The kicker is that /, /stand, and swap need to be contiguous. So if you need to resize any of those file systems then you will run into issues. Best suggestion would be to take an ignite that is interactive and resize in that case. Other than that I would suggest buying onlinejfs unless you really want to reboot and go into lvm maintenance mode when trying to resize certain file systems.

[Court Campbell]

My post has the potential to be misleading. You can always add extra swap.

[James R. Ferguson]

Hi Khilari:

> it is usually recommended to have twice the physical memory. Y is that. Secondly, in new installations can we just do a default filesystem install and just increase the size later on, before the application is mounted.

You don't offer the size of your physical memory which would be most useful to answering this question.

That aside, the 2x recommendation is a "one-answer-fits-all" one that I dislike.

Your primary device swap, which is the case under discusssion, can be *one-half* or equal to your physical memory size when pseudoswap is enabled. Everything depends upon your specific environment. Afterwards, you can add secondary swap space as necessary to accomodate your application requirements. Since primary swap space must use contiguous physical disk extents, it is virtually impossible to enlarge it later anyway.

Regards!

...JRF...

[DCE]

I have learned over time that the default filesystems sizes (espcially /, /tmp and /opt) tend to be too small for the real world. I make them larger at install time in order to avoid problems later on (espcially /) Yes, in an ideal world the sizes are adequate, but the real world has users in it..........

[Court Campbell]

>Yes, in an ideal world the sizes are adequate, but the real world has users in it..........

I nominate this for quote for quote of the day.