Share file on memory (like on tmpfs) via NFS (or alternatives)

waroros · 09-22-2009, 04:21 AM

Hi,

I want to store some file on tmpfs or any memory-based file system for better performance and share it via NFS or any protocal that can be used to mount folder. However, from the NFS faq, NFS doesn't support tmpfs.

Could anyone suggest a solution to achieve this?

MS3FGX · 09-22-2009, 09:09 PM

I tried it here on my machines and it looks like you need to put "fsid=0" in the export options for the share mounted on tmpfs, at which point it appears to work fine.

I have looked around online to figure out exactly what that option means, and it appears it is an NFS4 thing that sets that particular share as the root of the pseudo-filesystem. So this option might be a problem if you need to have multiple exports, though on my server I was still able to mount one of my other shares while I had the tmpfs share active.

Maybe somebody with more intimate knowledge of NFS could clear this up. I don't know if the option is safe to use in a production environment or not.

waroros · 09-22-2009, 09:56 PM

Thank MS3FGX for your suggestion. I'd try that out. I'm not sure if it works with NFSv3 since I used only NFSv3.

yyw1128 · 04-01-2011, 03:22 AM

Hi.
I've tried add option "fsid=0" on /etc/exports as MS3FGX told.

>
/data/tmpfs xxx.xxx.196.88(rw,fsid=0,async,no_root_squash)
<

But I still see error in /var/log/message

>
Mar 30 14:12:14 xen1 mountd[5902]: authenticated mount request from xxx.xxx.196.88:672 for /data/tmpfs (/data/tmpfs)
Mar 30 14:12:14 xen1 mountd[5902]: Cannot export /data/tmpfs, possibly unsupported filesystem or fsid= required
<

of course I'm using NFSV4 as below

[root@xen1 /]# rpcinfo -p

100000 2 tcp 111 portmapper
100000 2 udp 111 portmapper
100024 1 udp 666 status
100024 1 tcp 669 status
100011 1 udp 928 rquotad
100011 2 udp 928 rquotad
100011 1 tcp 931 rquotad
100011 2 tcp 931 rquotad
100003 2 udp 2049 nfs
100003 3 udp 2049 nfs
100003 4 udp 2049 nfs
100021 1 udp 54051 nlockmgr
100021 3 udp 54051 nlockmgr
100021 4 udp 54051 nlockmgr
100003 2 tcp 2049 nfs
100003 3 tcp 2049 nfs
100003 4 tcp 2049 nfs
100021 1 tcp 33064 nlockmgr
100021 3 tcp 33064 nlockmgr
100021 4 tcp 33064 nlockmgr
100005 1 udp 942 mountd
100005 1 tcp 945 mountd
100005 2 udp 942 mountd
100005 2 tcp 945 mountd
100005 3 udp 942 mountd
100005 3 tcp 945 mountd

What is the problem? Is there anything I have to do more setting?

Please let me know...

Thank you for reading.