OT: Linux Web hosting.
Martin Hodge
Posts: 1,246
I can remember back when I had a small web hosting business I would start to panic if the load avg got above 5.00. So I find it disconcerting when I SSH into my account at Bluehost and find this...
I've never seen it below 40! Of course when I bring this up with support I get the standard canned "Optimize your website" reply.
top - 10:27:52 up 58 days, 13:46, 1 user, load average: 85.44, 66.84, 52.65 Tasks: 4 total, 1 running, 3 sleeping, 0 stopped, 0 zombie Cpu(s): 73.4%us, 16.6%sy, 0.0%ni, 7.2%id, 2.5%wa, 0.0%hi, 0.4%si, 0.0%st Mem: 33002552k total, 26259892k used, 6742660k free, 1341120k buffers Swap: 8388600k total, 201644k used, 8186956k free, 13008872k cached PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 15831 mghdesig 20 0 14900 1188 952 R 0.3 0.0 0:00.08 top 7611 mghdesig 20 0 11472 1712 1328 S 0.0 0.0 0:00.02 bash 17012 mghdesig 20 0 260m 24m 8972 S 0.0 0.1 0:00.18 fcgiphp5 30394 mghdesig 20 0 15992 1768 1432 S 0.0 0.0 0:00.04 imap
I've never seen it below 40! Of course when I bring this up with support I get the standard canned "Optimize your website" reply.
Comments
Jeff
And what do those requests have to do? What hardware is this? Is it a virtual machine? etc etc.
Just 4 processes on the machine? Not with that kind of a cpu load. <sigh> Sometimes, I wonder what the heck modern day isps/web hosts teach their hardware folks (if they teach them anything at all) I find that calling a web host with questions on anything but billing meets with a lot of blaming and flat out wrong answers. So, for my sites these days, I just signed up as a reseller with a relatively inexpensive company (not godaddy) and resell web hosting to myself, it's cheaper, and I get unlimited disk space, mysql databases, bandwidth, and email addresses, and it's all for less than it'd cost me to maintain my own servers, so that makes me happy too.
Doing the exact same thing here.. totally cheaper to do this..
Funny part was a few years ago when I opened my shop in Downtown Orrville, the local cable company wouldn't put cable internet into my office without sending down their office folks to check to make sure that I wasn't setting up servers, Portmasters, etc. in violation of their contract. I laughed when they came down to look over my shop and give me a contract to sign. It's simply not economical to host your own stuff any more.
Jeff
I beg to differ -- I see "Mem: 33002552k total" and I read that number as 33,002,552 * 1024 bytes, or 32GB, not 32MB.
So 16 cores of....
Looking better ATM, but I wonder how many thousand sites are on this server.
And 34TB of virtual memory? Could that be right?
On MPU Linux boxes, a LA of 1 per core is equivalent to 100% utilization. They've got 2 CPUs which are 4 core with HT.
A LA of 85 / 16 = 5
I have a 4 core HT Core i7 machine at work, and I can say that HT helps, but it isn't an extra core, it's a lot like Chip's multi-threading in the P2.
Overall, that machine is grossly overloaded, well and truly beyond accepted best practices.
My guess is that they have a few thousand shared users on that machine and they don't implement any sort of fair share queuing. They would be better off to segregate the machine into 8 or 16 XEN VMs and balance the users across the VMs, then use the ban hammer on the abusive customers.
They only have 8GB of swap on that machine, the 34TB is probably the virtual address limit of the CPU--40 bits physical, 48 bits virtual
On a sixty four bit machine you have a 40 bit physical memory address, ie that many pins on the address bus. That is enough to access one terabyte of real RAM if you had it.
As shown above the internal virtual address is 48 bit, enough for 256 terabytes.
The key here is "virtual", Your processor can access that address range but it may not be real memory. When an access like that fails the OS can map it to swap space on disk.
Turns out I'd remembered wrong, icann charges (last time I checked anyway) about 10K a year for a block of ips, but the service I use for web hosting offers static ips for $2 a month, so no contest there.
It is absolutely mind boggling the things local isps believe they can charge for services.
I'd swear they all believe that nobody using their services has a clue about networking or actual cost of services provided.
It's quite sad really.
Then again, most folks in this town use a service that costs 60 or 70 bucks a month for 1.5 dsl, and for less than that this company provides 10MBPS service, so I guess they're somewhat justified in their views, but still, it rankles to be treated like a total ignorant savage when it comes to technology. *grumble*
All of which is very annoying as I like to be able to log into my home machine from outside sometimes. You can get around not having a static IP by using a dynamic DNS services.
Of course the next step is that you don't even get a public IP address so you can't reach your home machine at all without it creating a VPN tunnel to some external server.
Hopefully IPv6 will come soon and save us from all that nonsense. I'm just afraid the providers will find some way to bugger that up as well.
Amazingly I found that a couple of years ago every computer in Helsinki university had a public IP address. What luxury.
I read somewhere recently that IPv6 would allow every grain of sand on the Earth to have its own ip address, and that there would be enough left over to provide the same to the beaches of another 340 similar planets. So hopefully this will not be an issue in the future. Maybe someone was actually thinking ahead for once
I don't mind the cost, because to get the same performance elsewhere would be costly and I wouldn't have any guarantee of performance. VPS providers oversubscribe anywhere from a little to a lot, and they don't seem to give a hoot. I had to migrate a couple of out-sourced servers in-house at work because performance was inconsistent and costly. Now they are assigned to dedicated cores on our in-house VPS servers.
I've discovered web hosting accounts hammer the servers less, eat much less resources (in geneeral, not always), and is truly cheaper to outsource to one of the mega corps that specialize in such things. My monthly cost is exactly nothing, unless I need to renew a domain, or re-up a hosting package, but even that spread out over 12 months isn't much more than 10 bucks a month. I can't get a decent internet connection for that price, much less pay the electric bill for running the servers required to host multiple domains. These days, my needs are few, so hosting offsite makes sense. If it ever becomes a problem, I'll certainly host my own again, but for now, the reseller thing works for me.
As a sys admin I've always looked at a load average over the number of cpus (now cores) as an indication that something should be looked into. It's not indicative of a problem though. I've seen servers regularly run at a load average of 4-5 per cpu without any performance issues. Among the worst offenders are active DB servers and file servers.
I'm not saying that the server in question isn't overloaded but load average by itself means little. I have yet to find a single metric that will give you a clear indication of when a server is lightly, heavily or over loaded.