Re: [Sheflug] NFS Issues, Alternatives?

[Joel Cant <joel [at] xxxxxxxxxxxxxx>]

James Wallbank wrote:

> Hello All,
>
> At Access Space a problem seems to be emerging with our NFS server.
>
> For a few years the NIS/YP and NFS system we've had working has been 
> working really well, with a 500mHz CPU with 512mB RAM running a 
> dedicated IDE disk to serve everyone's home directories.
>
> However, recently we've found that it's possible to lock up the server 
> simply by moving large numbers of files in a single operation. We've 
> locked up the server with GFTP, by backing up websites containing 
> thousands of files (interestingly, wget doesn't prompt the same 
> problem) but more disturbingly, recently I dragged and dropped a 
> directory containing 3400 files and locked it up instantly.
>
> What happens is the machine completely locks up. You can ssh in to it, 
> but after it challenges you for a password, you never get a command 
> prompt - clearly it's very, very busy doing something else. The only 
> solution has been to give it the three-fingered salute from the 
> keyboard attached to the server. But even then, the machine starts to 
> shut down, gets to the step "Stopping NFS Services" and hangs. Then I 
> have to power cycle it to get it up again. Ouch!
>
> I haven't found any meaningful clues in /var/log/messages or 
> /var/log/syslog
>
> The machine is running Mandrake 9, and I have heard rumours of an 
> rpc.lockd bug on that version of the distro, so I've updated the 
> nfs-utils package in the hope that this will cure it for now. Failing 
> that, I'm intending to uprade to Mandrake 10, and possibly upgrade the 
> hardware too.
>
> I run two other NFS servers and both of them are running newer 
> versions of Mandrake, and they haven't had these problems, so I am 
> hopeful. Then again, they (the other servers) are less heavily used.
>
> However, LOTS of people say that NFS is always problematic. I wonder 
> whether any of you have implemented an alternative exported filesystem 
> that makes an ext3 device available to client machines in a totally 
> transparent way, preserving file permissions like NFS. As I understand 
> it (I haven't implemented it) Samba requires another layer of 
> passwords, and doesn't behave _exactly_ like a local drive, whereas 
> NFS does (except when it locks up!). Is this corect, or could I easily 
> implement Samba as an alternative exported FS?
>
> Of course, it's always possible that we have a hardware issue. Is an 
> IDE device simply not up to handling these sorts of many-thousands of 
> reads and writes in a single operation? Should we upgrade to SCSI or a 
> RAID array?
>
> Your thoughts welcome.
>
> Thanks,
>
> James
There are several althernatives, but unfortunalty there not as easy as 
NFS, I myself perfer NFS for its ease of use, there are various things 
like coda, smbfs and the likes, but really its a lot of pratting about 
for something NFS/NIS does well enough. I dont use mandrake so I'm not 
aware of any of its perculiarites, but it could be a kernel bug, or it 
might even be something more suspicious like a hard drive dying ( I've 
experianced HDD's being fine for ages then a huge amount of data 
shuffling causing them to mash themselves). Try a mandrake kernel 
upgrade,  i do belive there was an NFS fix in 2.6.7 for something to do 
with NFS lockups.

As for samba, it has tons of permission perculiarties, which if you can 
sort, make it a good FS to use, but i personally dont like it too much. 
I just wish NFS4 would hurry up and become stable, seems to have been in 
development for bloody ages. There is coda, but it requires everything 
to me mounted/stored under /coda which is a pain.

If it turns out to be a hardware issue, it may be worth investing in a 
raid array (SATA is cheap, if your budget is tight, plus SATA has much 
larger capacites than scsi)


Joel



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