The common thread is I/O to a MegaRAID raid5 device. Which is cause for concern since the primary function of both machines where I've encountered this problem is file-serving.
Perhaps I am just unlucky and have 2 bad MegaRAID cards in a row. I'm trying to understand this better, figure out if I am doing something wrong. My procedure is create a RAID 5 volume on the megaraid, do a slow init. Reboot the system into Linux, write a single large partition with parted, then put one or more logical volumes on the drive. The "hung" problem has cropped up under the following situations: (1) pvcreate on the disk (2) mkfs.ext4 on the volumes created on the disk (3) writes to the filesystem on the disk It's happened on 2 fileservers each with a megaraid. On 11/14/2012 10:19 AM, Jamie Duncan wrote:
is there a specific bug/bugs you're referring to? a hung task means that a process is sitting on a core waiting on a specific bit of I/O for > 120 seconds. Not the length of the entire process, mind you, which depends on countless inputs and outputs to complete, but something on the other side isn't answering for a very long time. It usually means an unhealthy system at some level. On Wed, Nov 14, 2012 at 11:04 AM, Ken Teh <[email protected] <mailto:[email protected]>> wrote: I've recently been encountering this problem trying to stand up a large RAID 5 disk server. My first encounter was when I was doing write speed tests. I thought I had solved this problem by letting the megaraid card complete a slow init of the volume before trying to create a linux filesystem on it and re-doing my speed measurements. But I have just now encountered it again on a new RAID 5 volume which I also let complete a slow init over the weekend. I was in fact trying to do a pvcreate on the volume when it hung. Can anyone shed some light? I see posts for it but everything I read suggests it's been taken care of. -- Thanks, Jamie Duncan 804.571.0458
