Sorry I mixed up my terminology. Let me better phrase my question. When originally running swift-ring-builder container.builder create, I set the partitions at 15 to give a total of 32768 partitions to split across 23 hosts with 12 disks each. Now I am replacing the container service on these 23 hosts with 4 hosts that have 1 disk.
Since I have 4 hosts with 1 disk each, do I calculate the weight of each of these disks as 2^15 / 4 so that the same overall partition numbers are available even though we're only using a handful of the disks? On Fri, Feb 28, 2014 at 11:20 AM, Pete Zaitcev <[email protected]> wrote: > On Fri, 28 Feb 2014 09:10:06 -0800 > Stephen Wood <[email protected]> wrote: > > > However I realize that the shard count is completely different now. > > What is a "shard count"? Do you have a document that uses such > terminology? > > > I > > originally used a partition value of 15 but this now seems much to high > for > > 4 servers with only disk each. > > So what? As long as there are no ill effects, it's all good. > Meaning if you have enough RAM to keep your ring once it's loaded, > then no problem, isn't it? It's not like your A+C servers magically > shrunk when you swapped the winchesters for SSDs, right? > > > Can I dynamically > > adjust the partition values after the swift ring has been created? > > No, you can't. > > > Or > > should I just take the disks on my 4 SSD hosts and put their weight as > 2^15 > > / 4 so the overall shard count stays the same? > > I am failing to make sense of the above sentence. Weight only matters > for builder scattering partitions at devices relative to each other. > So, if one replaces rotating media with SSDs, but keeps the cluster > running, the number of parititions stays the same, right? At that point > weights can be redefined at, say, 100, or any other number, without > any effect on total or per-device number of partitions. > > I think we need to circle back to the definition of the mysterious > "shard count" before we can get to the bottom of this. > > -- Pete > -- Stephen Wood www.heystephenwood.com
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