On Wed, Mar 21, 2012 at 11:13 AM, John R Pierce pierce@hogranch.com wrote:

On 03/20/12 2:54 PM, Gregory Machin wrote:

...

I have a CentOS 6.2 virtual machine in a vmware ESXi 4.0 host 4G Ram 4 virtaul cpus and with about 4 TB of disk space formatted with XFS . I'm seeing a lot of :

Mar 21 10:49:42 nzhmlfpr05 kernel: XFS (dm-4): xlog_space_left: head behind tail Mar 21 10:49:42 nzhmlfpr05 kernel:  tail_cycle = 129, tail_bytes = 20163072 Mar 21 10:49:42 nzhmlfpr05 kernel:  GH   cycle = 129, GH   bytes = 20162880 Mar 21 10:49:42 nzhmlfpr05 kernel: XFS (dm-7): xlog_space_left: head behind tail Mar 21 10:49:42 nzhmlfpr05 kernel:  tail_cycle = 5, tail_bytes = 333417984 Mar 21 10:49:42 nzhmlfpr05 kernel:  GH   cycle = 5, GH   bytes = 333417792 Mar 21 10:49:42 nzhmlfpr05 kernel: XFS (dm-7): xlog_space_left: head behind tail Mar 21 10:49:42 nzhmlfpr05 kernel:  tail_cycle = 5, tail_bytes = 333417984 Mar 21 10:49:42 nzhmlfpr05 kernel:  GH   cycle = 5, GH   bytes = 333417792

What would casue this ? A quick google , I found a post that indicated I should unmount and mount the file systems. I have live production data on this machine so I need to be careful. What is the best solution ?

what sort of physical disk storage is this vm using?   I'm wondering if perhaps this storage is unreliable with regards to write commits, or write ordering.

-- john r pierce                            N 37, W 122 santa cruz ca                         mid-left coast

Hi John

The ESX host is attache to an Infortrend iSCSI SAN with 2 RAID5 arrays , each array has 3 LUNs. The disk are 7200 SATA Seagate disks.The virtual machines run out off disks the reside on the LUNs..

I will have a look at the SAN and see if there are any errors.

Thanks