-----Original Message----- From: centos-bounces@centos.org [mailto:centos-bounces@centos.org] On Behalf Of Jean Figarella Sent: Wednesday, June 06, 2007 12:14 PM To: CentOS mailing list Subject: Re: [CentOS] NFS v4
Les Mikesell wrote:
Jean Figarella wrote:
Under real user load though it just fell on its arse very quickly and a quick fall back to v3 was implemented. Maybe the EL5 implementation behaves better?
I use one of my CentOS 5 boxen for low-load fileserver with NFS4. I've been noticing that although MP3s plays fine from that box, it can take a minute or two to write a dozen tags--something that should happen in the blink of an eye. I've been wondering what the problem is. Maybe it's NFS4!
I've been experiencing 5 to 20 seconds freezes ever since
I upgraded
my nfs server. This serves about 30 people. Anytime
someone writes a
big file to their home directory, the freezes happen. You can experience the freezes when browsing the internet, I guess because firefox is constantly writing data (cache, cookies, etc...). Other apps freeze up too.
Now the question on my side is: can I force centos4 for
serve nfs3 as
opposed to nfs4. If I am not mistaken this is dependent on
the client?
The reason Im asking is that if I can force the server to
serve nfs3
then the clients will default to nfs3 themselves. right?
Are these mounted with the sync or async option? If it is
sync, the
client waits for the physical flush to disk to happen on every operation, something that is horribly slow and that you
never do for
local disks except for transaction boundaries in databases
and other
unusual situations.
At first the sync option was being used, and the freezes happened very frequently. About a month and a half ago I started using async, and now I get far fewer freezes, like maybe 3 in an 8hr span.
You can also couple the async with the anticipatory scheduler so reads will get higher priority then writes which can help readers during a page-cache flush.
-Ross
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