Opinion about Xen
Posted by copahost, 09-14-2008, 06:51 PM I have read many topics here about Xen vs Virtuozzo vs Others. It's a common sense that if you resell hosting, Virtuozzo is the best option. But, we are thinking of reselling VPS with a Xen box, and I have a couple questions (that I haven't found answers anywhere yet): 1) How do you limit network bandwidth in it? tc, qdisc and cacti would be fine? 2) How do you limit CPU and IO usage? Does Xen offer any kind of report of each user, how much CPU, etc? 3) If anyone currently resell VPS with Xen, what are the issues or user complaints you currently have, from users who used Virtuozzo before? 4) Do VPS servers use a lot of disk IO? Would SATA disks(RAID-1 mirrored) be OK for it? 5) Does Xen limit the maximum VPS for each box?
Posted by jseymour, 09-14-2008, 08:43 PM I will answer what I can: 5) Does Xen limit the maximum VPS for each box? This (as I understand) is the case. Unfortunately I here that a later version of Xen will allow over selling. 4) Do VPS servers use a lot of disk IO? Would SATA disks(RAID-1 mirrored) be OK for it? I would never use a raid 1 in this situation - minimum raid 5. IO is pretty much the same as a normal OS. Not much overhead.
Posted by copahost, 09-14-2008, 08:56 PM No problem about overselling.. It's cheaper to buy 8GB ram than pay for Virtuozzo subscription.. With 8GB ram you can sell e.g. 31 256mb vps
Posted by fog, 09-15-2008, 09:37 AM I run a Xen box, but it's just a few friends, not sold to the public. Our disk usage is no different than if it were a "normal" server. There's no hard limit. But it doesn't really lend itself to overselling since you can't really "burst" RAM. If you have 2GB RAM, and give 512 MB to each client, you're only going to get 4 on there. (Actually, 3, since you can't run "Dom0" with no RAM...) There does exist a "max_mem" setting to allow virtual machines to use more RAM, but I'm not sure how it works -- it just flat-out doesn't work on ours, but we have enough RAM for what we do that it doesn't matter.
Posted by PCS-Chris, 09-15-2008, 02:12 PM 1) How do you limit network bandwidth in it? tc, qdisc and cacti would be fine? Not 100% sure on this one, I guess you could use cacti although we use HyperVM which monitors and logs bandwidth usage. 2) How do you limit CPU and IO usage? Does Xen offer any kind of report of each user, how much CPU, etc? CPU can basically be equal share or you can give a specific amount to each VM. 3) If anyone currently resell VPS with Xen, what are the issues or user complaints you currently have, from users who used Virtuozzo before? Why wasnt my old OpenVZ VPS this fast? Joking aside, we have had no complaints at all, only positive comments. 4) Do VPS servers use a lot of disk IO? Would SATA disks(RAID-1 mirrored) be OK for it? Depends on the size of the node and how many VPS you put on each node. You will want RAID5 or RAID10 for larger setups though. 5) Does Xen limit the maximum VPS for each box? You can only create VPS within the resources you have (you cant oversell) which is how it should be.. There is no fixed limit, but obviously if you had a box with 1GB Ram, you could create 3x VM's with 256MB RAM. 256MB is reserved for the node, although you can change this.
Posted by mellow-h, 09-16-2008, 10:46 AM Will only confirm about the cacti, it works fine for my xen box Xen is better in my opinion comparing with OvenVZ as it won't allow you to oversell and provide dedicated performance.