Re: [Xen-users] IOwaits over NFS

["Geoff Galitz" <geoff@xxxxxxxxxx>]

 

 

We`ve used various NFS parameters in our testing to resolve this.  Here are three different  examples of what we have used on a single machine, with no significant improvement:

 

1) defaults,auto,tcp,bg,hard,intr,noatime 0 0

2) auto,noatime,rsize=32768,wsize=32768,bg,nfsvers=3,intr,tcp,retrans=0 0 0

3) noatime,bg,intr,nolock,tcp      0 0

 

 

Thanks.

 

 

From: Ribeiro Emerson Gomes

Sent: Tuesday, September 14, 2010 4:20 PM

To: Geoff Galitz ; xen-users@xxxxxxxxxxxxxxxxxxx

Subject: RE: [Xen-users] IOwaits over NFS

Please inform the parameters you use in fstab when you mount your NFS share.

Something like this:

<server>:/<share> <mountpoint> nfs rsize=8192, wsize=8192, timeo=14, intr, tcp, bg, rw, bg, hard, nointr, rsize=32768, wsize=32768, tcp, actimeo=0, vers=3,timeo=600

 

 

Emerson

 

 

-----Original Message-----
From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx [mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Geoff Galitz
Sent: Tuesday, September 14, 2010 11:04 AM
To: xen-users@xxxxxxxxxxxxxxxxxxx
Subject: [Xen-users] IOwaits over NFS

 

Hello.

We have a number of Xen 3.4.2. boxes which have constant iowaits at around
10% with spikes up to 100% when accessing data over NFS.  We have been
unable to nail down the issue.  Any advice?


System info:


release                : 2.6.18-194.3.1.el5xen
version                : #1 SMP Thu May 13 13:49:53 EDT 2010
machine                : x86_64
nr_cpus                : 16
nr_nodes               : 1
cores_per_socket       : 4
threads_per_core       : 2
cpu_mhz                : 2261
hw_caps                :
bfebfbff:28100800:00000000:00000340:009ce3bd:00000000:00000001:00000000
virt_caps              : hvm
total_memory           : 32758
free_memory            : 3974
node_to_cpu            : node0:0-15
node_to_memory         : node0:3974
xen_major              : 3
xen_minor              : 4
xen_extra              : .2
xen_caps               : xen-3.0-x86_64 xen-3.0-x86_32p hvm-3.0-x86_32
hvm-3.0-x86_32p hvm-3.0-x86_64
xen_scheduler          : credit
xen_pagesize           : 4096
platform_params        : virt_start=0xffff800000000000
xen_changeset          : unavailable
cc_compiler            : gcc version 4.1.2 20080704 (Red Hat 4.1.2-44)
cc_compile_by          : root
cc_compile_domain      : gitco.tld
cc_compile_date        : Wed Nov 11 21:16:28 CET 2009
xend_config_format     : 4


And lsmod from a VM:

Module                  Size  Used by
nfsd                  284041  17
exportfs               38849  1 nfsd
auth_rpcgss            81889  1 nfsd
ipv6                  424737  24
xfrm_nalgo             43333  1 ipv6
crypto_api             42945  1 xfrm_nalgo
i2c_dev                43849  0
i2c_core               56129  1 i2c_dev
nfs                   289549  1
lockd                  99185  3 nfsd,nfs
fscache                52385  1 nfs
nfs_acl                36673  2 nfsd,nfs
sunrpc                197513  18 nfsd,auth_rpcgss,nfs,lockd,nfs_acl
iptable_filter         36161  1
ip_tables              55329  1 iptable_filter
x_tables               50377  1 ip_tables
dm_mirror              54345  0
dm_multipath           55385  0
scsi_dh                41665  1 dm_multipath
scsi_mod              197337  1 scsi_dh
parport_pc             62313  0
lp                     47121  0
parport                73293  2 parport_pc,lp
pcspkr                 36289  0
xennet                 61129  0 [permanent]
dm_raid45              98897  0
dm_message             36161  1 dm_raid45
dm_region_hash         46401  1 dm_raid45
dm_log                 44993  3 dm_mirror,dm_raid45,dm_region_hash
dm_mod                100753  4 dm_mirror,dm_multipath,dm_raid45,dm_log
dm_mem_cache           39617  1 dm_raid45
ext3                  168529  1
jbd                    94257  1 ext3
uhci_hcd               57561  0
ohci_hcd               56053  0
ehci_hcd               65869  0
xenblk                 50729  1

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