Alain, Can you post your mdadm --detail /dev/md0 output here as well as your iostat -x -d when that happens. A bad ephemeral drive on EC2 is not unheard of.
Alexis | @alq | http://datadog.com P.S. also, disk utilization is not a reliable metric, iostat's await and svctm are more useful imho. On Sun, Mar 31, 2013 at 6:03 AM, aaron morton <aa...@thelastpickle.com>wrote: > Ok, if you're going to look into it, please keep me/us posted. > > It's not on my radar. > > Cheers > > ----------------- > Aaron Morton > Freelance Cassandra Consultant > New Zealand > > @aaronmorton > http://www.thelastpickle.com > > On 28/03/2013, at 2:43 PM, Alain RODRIGUEZ <arodr...@gmail.com> wrote: > > Ok, if you're going to look into it, please keep me/us posted. > > It happen twice for me, the same day, within a few hours on the same node > and only happened to 1 node out of 12, making this node almost unreachable. > > > 2013/3/28 aaron morton <aa...@thelastpickle.com> > >> I noticed this on an m1.xlarge (cassandra 1.1.10) instance today as well, >> 1 or 2 disks in a raid 0 running at 85 to 100% the others 35 to 50ish. >> >> Have not looked into it. >> >> Cheers >> >> ----------------- >> Aaron Morton >> Freelance Cassandra Consultant >> New Zealand >> >> @aaronmorton >> http://www.thelastpickle.com >> >> On 26/03/2013, at 11:57 PM, Alain RODRIGUEZ <arodr...@gmail.com> wrote: >> >> We use C* on m1.xLarge AWS EC2 servers, with 4 disks xvdb, xvdc, xvdd, >> xvde parts of a logical Raid0 (md0). >> >> I use to see their use increasing in the same way. This morning there was >> a normal minor compaction followed by messages dropped on one node (out of >> 12). >> >> Looking closely at this node I saw the following: >> >> http://img69.imageshack.us/img69/9425/opscenterweirddisk.png >> >> On this node, one of the four disks (xvdd) started working hardly while >> other worked less intensively. >> >> This is quite weird since I always saw this 4 disks being used the exact >> same way at every moment (as you can see on 5 other nodes or when the node >> ".239" come back to normal). >> >> Any idea on what happened and on how it can be avoided ? >> >> Alain >> >> >> > >
