Maximum number of groups in Linux

Question

I have several questions about linux groups

Is there a limit to the number of groups a user can create?
Is there a limit to the total number of groups in a system?
Is there a limit to the number of groups a user may be a member of?
Do large numbers of groups (and users as well) degrade performance? Will 1000 users with 1000 groups each be substantially slower than 1 user and no groups (discluding system generated users/groups)

I'm trying to come up with a website that bridges the gap between SQL user databses and actual linux users.

Ignacio Vazquez-Abrams · Answer 1 · 2011-11-04 04:51:28Z

up vote 5 down vote accepted

Users can't create groups, only the superuser can. And the superuser can create up to the system maximum minus existing groups.
Modern Linuxes have a 32-bit gid_t, so just short of 4.3e9.
Depends completely on the NSS being used. I don't think the files NSS has a limit.
Again, depends on the NSS. Using something like LDAP would be faster than files obviously.

answered Nov 4 '11 at 4:51

	How do I find out what my 'system maximum' is. I read here it is 16 or 32...that is pitiful if it's the case. – puk Nov 4 '11 at 5:00
	Why are you reading Solaris documentation when you've tagged the question "linux"? – Ignacio Vazquez-Abrams Nov 4 '11 at 5:07
	that's a relief, but the article says `You simply cannot have more than 16 groups and use AUTH_SYS`. It seems the problem is more complicated than at first glance. – puk Nov 4 '11 at 5:10
	I got linked to that page from another linux site. – puk Nov 4 '11 at 5:11
	So then don't use NFSv2 or v3. – Ignacio Vazquez-Abrams Nov 4 '11 at 5:13

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