| Posted by DerAndy, 10-27-2014, 05:41 PM | | Hello everyone,
I'm working on designing the server system for a new web hosting company. The goal is to get known for quality, not so much for being cheap. So I need a stable system with good availability and performance. Sadly that doesn't come with an unlimited budget...
To start with I think about deploying two servers as hypervisors in a HA configuration and put the services in virtual machines. That way I'd get continuous service in case of hardware failure of one server. As the main focus of the business will be on Windows based hosting and Exchange hosting, the hypervisor I have in mind would be Hyper-V.
To finally get to the question, I'm wondering about what to use for storage. After all, I'd need that to be HA, too.
I could either go with a hardware solution (maybe Fujitsu Eternus) or a virtual SAN solution (maybe StarWind or DataCore). I'm calculating with about 2-3 TB net space to start out with, and for that it seems the price point would be similar between a single Eternus (with dual controllers) and a 2-Node software solution, calculating needing double the drive count and additional computing power. Well, DataCore would probably be a bit more expensive. For expansions the cost for the software solutions would be higher because I'd need twice as many hard disks and additional software licenses.
What do people here think about those options in terms of availability, stability and performance?
According to the sales people a dual controller Eternus would be "almost" impossible to go down except for hard disk defects. Doesn't stop them from selling mirrored solutions with two of them and transparent failover. I'd think that a software solution would be more stable in that regard because really everything to the last screw is redundant. On the other hand I'm wondering it if's such a good idea to run a SAN on top of Windows, especially as it has other workloads to run. Plus as I read it the virtual SAN could get inconsistent if both servers go down at the same time (mainly for power issues) because it doesn't know which has the current data. Wouldn't be a problem for the hardware SAN as there's only one set of data...
So it's a pretty confusing issue for me, and I'm sure it's one others have wrestled with before so hopefully you can help me with your thoughts.
Thanks!
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| Posted by Srv24x7, 10-28-2014, 10:10 AM | | Hi,
I think SAN would be the best option to go with Failover clustering and HA. With having this, you are having all the VPS file in a shared storage, so the front end server will only serve the contents fetched from common shared storage and in case of one server failure, other server will take its place and still continue to fetch the same data from the common storage.
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| Posted by martijnatlico, 10-28-2014, 11:14 AM | | You can basically expect dual-controller SAN units like the Fujitsu Eternus to run hassle-free for three to five years. On our comparable Dell SAN the only issue we've ever had was a failed backup battery which required the replacement of one of the controller modules. The downtime was 0.0 seconds. Thanks to the multipath drivers in your OS the hosts that were connected to the problem controller failed over to the other one seamlessly and we could easily hot-swap the controllers. Uptime with our SANs (all single standalone units) has been 100.0% so far. You just don't get that with a 'SAN' running on top of Windows. I like how these things don't even have a power button (at least not the Dell and EMC ones we have), you just plug em in and don't turn them off until you take them out of service years later.
Realistically of course you can have bad luck with firmware issues or multiple failing drives but not more so with a software solution on top of Windows or Linux.
I'm currently looking into VMWare Virtual SAN for a new deployment and it seems very enticing, but I'm very much tempted to stick with traditional SANs for now since it's a proven technology and I've personally found them so extremely reliable. Of course a single SAN equals a single point of failure, but complex network partitions can throw distributed systems like Virtual SAN off course easily as well (causing downtime and even data loss).
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| Posted by DerAndy, 10-28-2014, 12:39 PM | | Thanks for your opinions so far
True there's no perfect solution, but that's what backups are for.
I do like the new VMware solution in theory, but it's just too expensive for a small setup like mine (plus it needs three servers). And it's a pretty strong vendor lock-in as you can't access it from the "outside"...
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| Posted by martijnatlico, 10-28-2014, 01:38 PM | | Yeah the pricing on VMWare Virtual SAN is pretty steep, I guess their parent company (EMC) doesn't want Virtual SAN cutting into it's SAN business. A small scale Virtual SAN solution for three nodes is basically as expensive as a decent entry-level iSCSI SAN.
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| Posted by YUPAPA, 10-29-2014, 04:24 AM | | I'd go for a traditional SAN. I've dealt with dell, emc and hds and have never encountered any issue other than firmware related. The SANs were extremely reliable.
For software like SAN, you might have issues with its software, and the hardware of the servers. I've seen people getting into situations where their problems are throwing in between vmware and their hardware vendor in order to get them fixed. And looks like you'll be limited to 1Gbps unless you can invest 10Gbps ethernet.
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