Back in June, I wrote about my switch to VPSLink for my virtual private server (VPS) host.
Now it’s 6 months later, my initial contract is up, and it’s time to consider whether to renew it.
Overall, VPSLink has worked out reasonably well. I have their Link-4 plan, which provides 512MB RAM, 20GB of disk storage, and 500GB of bandwidth for $40/mo (or down to $33/mo if you pay for 12 months in advance).
Reliability and Uptime
VPSLink has been reasonably reliable. I wouldn’t say that they have been exceptionally reliable, though.
- Back in July, the server was down for more than 8 hours. vpslink support blamed it on filesystem corruption; they rebooted, the system came up, FS went into readonly mode, so they went back down for fsck. I don’t know what FS they use.
- In October, an outage of about 30-60 minutes that apparently was due to load problems on the host. The control panel also was broken during this time. Apparently there is a reboot queue, and the system can only reboot one customer’s VPS at a time, and everybody wanted to reboot. But the UI was not really designed for this situation and presented very confusing status messages.
- In November, a kernel panic caused an outage of about 60 minutes.
- Various other outages that were resolved fast enough that I never emailed them about it.
They have generally responded to support requests in a reasonable amount of time, and support has been approximately as helpful as I’d expect.
Overall, there’ve been a few issues but, aside from that 8-hour outage in July, nothing especially remarkable.
VPSLink has a “control panel” where you can reboot, start, or stop your virtual machine. You can see how much bandwidth you’ve used in a month, your IPs, and billing information.
You can also create support requests and view the status of support requests there. You can also view all correspondence on a given ticket, and add new correspondence to it — a nice touch that’s useful if your email is down because your VPS is down.
The reboot/start/stop facility didn’t work during one outage, though.
The 20GB of disk space is nice to have, though I never used it all. No complaints there.
But the memory setup is rather strange. This may be because VPSLink is using OpenVZ instead of its more popular (and featureful) commercial counterpart Virtuozzo, or something such as Xen.
Those that have used OpenVZ/Virtuozzo know there is a /proc/user_beancounters file in the virtual environment that reports on the limits of resources allocated to your virtual server. VZ lets the server admins regulate the amount of resident RAM, swap, inodes, pending IP connections, amount of virtual RAM, etc, etc. About 3 dozen items in total.
Unlike some companies like JohnCompanies, VPSLink was not willing to make any adjustments to this file for me. For instance, my mail server may need more simultaneous open files than they have by default, but they wouldn’t work with me to make reasonable adjustments.
But the larger problem was with regard to RAM. This was particularly annoying. VPSLink does not permit any access to swap, so the 512MB is what you get. But tools like top show the entire memory allocation on the host, and are mostly useless in tracking down your own usage.
You can look at the privvmpages entry in /proc/user_beancounters to get an idea of your current usage, but that’s it. There is a script on their wiki that will turn this into a more useful number, but again, it’s not the most helpful.
The minute you try to allocate anything past 512MB, your processes start getting killed. According to /proc/user_beancounters, even though my system normally hovers around 70% of that 512MB allocated, I’ve had 290,567 instances where a process has been refused its request to allocate memory since the last reboot. Such instances usually cause a process to crash.
Other Virtuozzo companies like JohnCompanies will give you “burstable RAM”, so if others aren’t using their full RAM allocation at the moment that your machine goes over your regular limit, you can go over it to a certain extent. That was very effective at preventing crashes during times of higher than usual memory usage, and I never had trouble with this at JohnCompanies.
I’ve had a lot of trouble with VPSLink because of these hard, no-exceptions limits. Getting hit by the Google bot at the same time as the MSN bot could raise memory usage enough that processes would start getting killed. Depending on which process it is, it could take down cron, apache, the mail server, whatever. And there is no log of which processes die because of this.
In normal circumstances, this wouldn’t pose even a noticeable impact to a server; inactive bits could be swapped out, etc.
I am also suspicious of exactly how OpenVZ calculates memory usage. Since moving to a physical Linux box, my memory usage seems to be much lower than the privvmpages would seem to indicate, even though it’s running the exact same code.
So I had some outages on my server that were caused by OpenVZ memory limits, which didn’t get listed in the overall outages above.
This problem is the #1 reason I’m leaving VPSLink.
Overall performance has been acceptable. The CPU speed appears to be reasonable and about as expected.
The disk performance has been more problematic, however. It tends to be rather slow. There have been times when I can type “ls” in a directory with about 10 files and it takes 5-10 seconds to respond. And I wasn’t even using “-l”.
Now that sort of thing is certainly the exception. But it makes databases — and websites that rely on databases — very slow.
The performance measurements over at RealMetrics also show VPSLink as being at the bottom of the pack for disk performance.
VPSLink is a reasonable value, and if monthly cost is important to you, probably a good choice. Don’t expect it to be spotless, though. I would call the overall experience pretty average. Nothing too spectacular in either direction in any respect.