> Given the advice to use a single RAID 0 volume, I think that's what I'll do. > By system mirror, you are referring to the volume on which the OS is > installed? Yes. I was thinking about a simple RAID 1 OS volume and RAID 0 data volume setup. With the Commit Log on the OS volume so it does not compete with cassandra for iops. > sense in my case to build or maintain a large cluster. I wanted to run a > two-node setup (RF=1, RCL=ONE, WCL=ALL), You would be taking on the operational concerns of running cassandra without any of the payoff for having a cluster.
> each with several disks having large capacity, totaling 10 - 12 TB. Is this > (another) bad idea? Yes. Very bad. If you had 6TB on average system with spinning disks you would measure duration of repairs and compactions in days. If you want to store 12 TB of data you will need more machines. Hope that helps. ----------------- Aaron Morton Freelance Developer @aaronmorton http://www.thelastpickle.com On 18/09/2012, at 3:53 AM, Casey Deccio <ca...@deccio.net> wrote: > On Mon, Sep 17, 2012 at 1:19 AM, aaron morton <aa...@thelastpickle.com> wrote: >> 4 drives for data and 1 drive for commitlog, > How are you configuring the drives ? It's normally best to present one big > data volume, e.g. using raid 0, and put the commit log on say the system > mirror. > > > Given the advice to use a single RAID 0 volume, I think that's what I'll do. > By system mirror, you are referring to the volume on which the OS is > installed? Should the volume with the commit log also have multiple disks in > a RAID 0 volume? Alternatively, would a RAID 1 setup be reasonable for the > system volume/OS, so the system itself can be resilient to disk failure, or > would that kill commit performance? > > Any preference to hardware RAID 0 vs. using something like mdadm? > > A word of warning. If you put more than 300GB to 400GB per node you may end > experience some issues such as repair, compaction or disaster recovery taking > a long time. These are simply soft limits that provide a good rule of thumb > for HDD based systems with 1 GigE networking. > > Hmm. My hope was to be able to run a minimal number of nodes and maximize > their capacity because it doesn't make sense in my case to build or maintain > a large cluster. I wanted to run a two-node setup (RF=1, RCL=ONE, WCL=ALL), > each with several disks having large capacity, totaling 10 - 12 TB. Is this > (another) bad idea? > > Casey
