Linked by David Adams on Thu 20th Nov 2008 04:19 UTC
General Unix Linux and other Unix-like operating systems use the term "swap" to describe both the act of moving memory pages between RAM and disk. It is common to use a whole partition of a hard disk for swapping. However, with the 2.6 Linux kernel, swap files are just as fast as swap partitions. Now, many admins (both Windows and Linux/UNIX) follow an old rule of thumb that your swap partition should be twice the size of your main system RAM. Let us say I’ve 32GB RAM, should I set swap space to 64 GB? Is 64 GB of swap space really required? How big should your Linux / UNIX swap space be?
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XDMCP/NX server
by sbergman27 on Thu 20th Nov 2008 13:04 UTC
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Just as a datapoint, I have a server running Fedora 8 x86_64, about 60 Gnome desktops via a mix of XDMCP on the lan and NX on the wan. (Web browsing, email, OpenOffice, etc. Standard business stuff.) It's also a samba server, database server for a COBOL C/ISAM -> SQL gateway, about a hundred instances of a curses-based point of sale and accounting system, etc. It currently has 8GB of ram, and uses a maximum of about 7GB of the 16GB of swap I have allocated. It is at the point that performace is still (just) acceptable throughout the work day. We'll be adding 4 more GB of ram soon, which maxes that server out. (For x86_64, my rule of thumb is at least 128MB per Gnome user. At least 96MB per user for x86_32.)

As a Unix (and later Linux) admin since 1988, I am always surprised when these kinds of discussions fixate on the eMachines PC in the living room.

Reply Score: 3

RE: XDMCP/NX server
by siride on Thu 20th Nov 2008 13:38 in reply to "XDMCP/NX server"
siride Member since:

Wouldn't it make sense to have more than one machine do what you are making that poor server do? It seems strange to have a machine that runs user desktops also be running the database and point-of-sale stuff, among other things.

Reply Parent Score: 2

RE[2]: XDMCP/NX server
by sbergman27 on Thu 20th Nov 2008 13:54 in reply to "RE: XDMCP/NX server"
sbergman27 Member since:

Wouldn't it make sense to have more than one machine do what you are making that poor server do?

No. More machines mean more administration. I cannot and would not go to management to say we need to allocate funds to buy another server to increase our administration load. People pay big bucks for virtualization tools to *consolidate* their servers. Why would I push for server *proliferation*? I segregate functions only when security or other practical considerations require it.

BTW, the C/ISAM -> SQL gateway operates on the COBOL files used by the POS/Accounting system, and the desktop users use the POS/Accounting system as one of the application on their desktops. It makes a great deal of sense to keep all the disk and socket accesses local.

Although performance is only "OK" right now, it will be excellent in about a week when we add the memory. The dual 3.2GHz Xeons are only moderately loaded, being shared by only 60 users. (Multicore is vastly over-hyped for standard business desktop workloads. But that's a topic for another post.)

Even after all these years, I still find Unix/Linux multi-user efficiency to be amazing.

Edited 2008-11-20 14:01 UTC

Reply Parent Score: 3

RE: XDMCP/NX server
by helf on Fri 21st Nov 2008 00:53 in reply to "XDMCP/NX server"
helf Member since:

Maxes at 12gb of ram? That is kinda weird.

Reply Parent Score: 2