Repeated error message istgt_lu_disk_lbwrite_ats: ***ERROR*** compare failed

[patja]

I have a new 8.0.1 RC2 install on an ESXi 5.0 vm. I am using ZFS Raid-Z2 with 6 2TB drives on a passthrough SAS card. I've copied about 3 TB of files over and setup some iSCSI extents to host other VMs on the ESXi box. I am seeing regularly repeated "compare failed" error messages from FreeNAS in /var/log/messages, like these:

Code:

Sep 24 20:11:37 jabba freenas[1837]: Popen()ing: /sbin/zfs list -t snapshot -H -S creation
Sep 24 20:11:38 jabba freenas[1837]: Popen()ing: /sbin/zfs list -t snapshot -H -S creation
Sep 24 20:11:52 jabba istgt[1910]: Login from iqn.1998-01.com.vmware:esxi-61d97833 (192.168.0.182) on iqn.2011-03.example.org.istgt:tgvm LU3 (192.168.0.184:3260,1), ISID=23d000001, TSIH=3, CID=0, HeaderDigest=off, DataDigest=off
Sep 24 20:15:01 jabba freenas[11014]: Popen()ing: zpool list -H -o health ZFS
Sep 24 20:19:23 jabba istgt[1910]: istgt_lu_disk.c:4129:istgt_lu_disk_lbwrite_ats: ***ERROR*** compare failed

I am not seeing symptoms of a general problem, but these repeated errors concern me.

Should they be a concern? If so, what do they indicate? What is being compared and why might it be failing?

Thanks for any help or insight!

-Pat

 

[jgreco]

Not absolutely *positive* about this, since the code isn't really documented.

istgt_lu_disk_lbwrite_ats writes data and then reads it again, and issues this warning if the data read doesn't match what was written.

"ats" seems like maybe it's an "atomic test and set" operation of some sort. I have no idea what it's doing.