Addressing Matt's [comments] Against Xen

Jun 3, 2007

I would like properly address Matt Ayer's (WiseOne) continual claims that user created swap in xen can lead to disastrous situations. This doesn't make any sense from a Kernel point of view. Linux kernel treats Swap not as a additional memory, but as auxiliary storage, and will use it only sparingly. So a larger than ordinary swap has effectively zero impact on performance.

Quote:

I just don't have the time. Try this quick though. Create as many 64MB RAM Xen VPS's as you can, make a 1GB swap file inside each VPS, run a memory hogger, and then finally watch your system die due to horrific disk I/O. Not fun, I'll tell you that.

Conclusion: User controlled swap in a shared environment is a very, very, very bad thing.


Now let us assume there is a hostile user who is egregiously bent on creating excess disk I/O for the host and has purposefully hired vps to enact his revenge on the provider. Further assume that, for this nefarious purpose he has taken a 64MB xen and is running a full 1GB real memory allocated workload (To get create such a load itself would be difficult unless he writes his own programs to do this). Now note that, for the offending vps, the impact of the disk I/O is at the memory level, while the impact on the host is at the disk level. So very trivially, the vps would be so crippled to make it pretty much useless much before this starts having significant effect on the main server. And if engendering excess disk I/O is the sole purpose of user, then all he need to do is write a program to consecutively load and free all the files in the entire harddisk. This will create worse disk I/O than the convoluted method of using large swap. And the latter can be done on both virtuozzo and Xen--though I think in recent versions both have methods to throttle disk I/O.

The problem that UnixShell ran into with Xen was owing to their use of Snapshot, which is something that's prohibited, unless of course, you are running on a desktop with a single virtual machine. LVM snapshot will exactly double the disk I/O. The real problem that the usage is insidious and will not affect the actual vps that's leading to the excess load, but will affect the entire server as a whole.

Xen does have some drawbacks, but it can have all the important features which most providers here think are unique to virtuozzo.

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Addressing VLANs On Extreme Summit 48

Feb 13, 2007

Having a slight problem working with one of our Extreme Summit 48 (ugh) switches - I've figured out most of the basics, but I can't seem to find any way to add a secondary IP address to a VLAN! This, I would have thought, would be a pretty basic feature to have. Typing "config vlan [vlanname] ipaddress 1.2.3.4/24" works for setting the primary IP, but I can't figure out how to add any more - and doing the command again just overwrites the first one.

So... does anyone have any tricks up their sleeve, or is this something that Extreme neglected to add to this model switch?

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Apr 30, 2009

I have purchased a domain, and installed WAMP on my local computer. Now, I want to attach the domain name to WAMP such that when I entered my designed site on WAMP on my computer, I'll see my own domain instead of C://localhost/.../...

I have been told that the company that owns my domain should address its DNS to my own DNS?

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Plesk 12.x / Linux :: Plus Addressing With Dovecot Does Not Work

Feb 3, 2015

I did the following configuration:

Postfix
in the /etc/postfix/main.cf I added the following configuration parameter
recipient_delimiter = +
Managed a sieve script in webmail which contains the following:
1: # Sieve Filter
2: # Erzeugt von Ingo (http://www.horde.org/apps/ingo/) (03.02.2015, 02:53:39)
3: require "fileinto";
4: # Plustest
5: if address :all :comparator "i;ascii-casemap" :contains "To" "+plustest" {
6: fileinto "INBOX.plustest";
7: stop;
8: }

I created a folder in my INBOX with the name plustest, now I sent me an email from an outside freemail-account to see if it works. In the logfile /var/log/maillog I can see the following entry:

Feb 3 15:06:25 mail postfix-local[18290]: cannot chdir to mailname dir <name>+plustest: No such file or directory
Feb 3 15:06:25 mail postfix-local[18290]: Unknown user: <name>+plustest@<dom.tld>
Feb 3 15:06:25 mail postfix/pipe[17708]: 0ECAF4C1B3: to=<name+plustest@dom.tld>, orig_to=<aliasname+plustest@dom.tld>, relay=plesk_virtual, delay=0.61, delays=0.52/0/0/0.09, dsn=2.0.0, status=sent (delivered via plesk_virtual service)

I changed my real name to <name> and my domainname to <dom.tld> in this post.

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RockMyWeb Comments

Jul 18, 2007

I've been with RockMyWeb.net for exactly one month now, and I want to share my experiences. This is a one-month experience, so it will be mainly about new purchase and initial support. This is a quite long post, I wasn't really considering to write that long.

I'm a shared hosting provider in local language. One of the websites I host has grown too much to be on a shared server. It didn't even fit on a standart VPS with 256 MB guaranteed, 1 GB burst ram. So we decided to go with VirtuallyDedicated,
[url]

with the plan 1.5 GHP, since it was better than a dedicated server with pentium-4 processor and 1 Gb ram, and was cheaper. The website being hosted is www.trforumcu.com, along with a dozen of small websites.

Purchase:
I requested a custom quote, with cPanel and management, less diskspace. They prepared the quote within 3 hours, I paid within 24 hours, they set up the VPS within 12 hours, including initial management. The process was painless.

Initial support:
We had some requests about the VPS within the first 3 days, before moving the websites. The tickets was being responded within 2 minutes, some being even within the same minute. That is the fastest response time I've ever got from a provider (I've been with 6 different VPS providers, as far as I remember.) It looks like someone is always waiting for tickets at any time. My tickets were usually being opened in their nights, due to the time zone difference between us. I'm very satisfied with their knowledgeable support.

One point about their support is that they act as if the customer is their friend. I mean, They don't send this reply:

Quote:

Hello,

The issue is being worked on.

Best Regards,
Blah Blah
Customer Service Represantative
RockMyWeb.net

Instead, they send this within the minute:

Quote:

Hi, I'm having a look at it right away.

I, myself, actually use the former type of reply to my own customers. But the latter was quite nice, considering they are sending it right away, and start working on the actual problem within the minute. And they are solving the problem, too.

Support within the month:
After initial configurations, we had some problems. Our website was using too much resources, and the server needed to be optimized a little bit. I opened a ticket. They replied 4 times, without my reply. They informed me about the process well. After 4 replies, they said the server should be fine now.

After 2 days, they sent me an email, asking if I'm satisfied with the optimization. This is the first time I'm getting an email from a provider after some time, asking about my satisfaction.

We also had a cPanel licence issue (cPanel suddenly forgot about its licence, and started saying "cannot read licence file"). This was solved within 36 hours. They said the problem needs to be fixed by cPanel support staff itself, and their support over weekend is not the best. They kept updating me every 12 hours, saying they are waiting the cPanel staff. After 36 hours, the issue was fixed.

About their system:
Their VPS technology is different from my other VPSs with other providers. They don't use Virtuozzo, they use some kind of custom system (it doesn't seem to be VMware or like). This is the only thing I can complain, I was used to VZ and their custom panel is quite different. They provide VPS restart utility, and this is actually the only thing I need from a VPS remote panel.

They don't provide equal-share CPU, they allocate guaranteed CPU. This was very important for us, because the website we were hosting was being kicked off the VPS providers due to high CPU usage. With rockmyweb's allocated CPU, we are not interfering with other VPSs on the system, and we feel quite more comfortable. Also, we have 1.5 processor cores guaranteed, much higher than any other VPS providers will provide for this cost.

Their backup system is also satisfying. They charge 0.25 per GB backup used, not allocated. So I don't pay for unused backup space.

Overall, I'm satisfied with their service, and very happy with their support over the first month. I'll update this topic with additional information and comments (both positive and negative) over the time.

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Mar 25, 2007

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[url]

has anyone tried to put this board into 1u case? seem like a sweet deal

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Nov 7, 2007

I am interested to setup two Ironport appliances in my company network. As the current company is about 120 users, and each user send and receive an average of 100 email per day (including newsletter, signup, etc) it’s about 12000 email a day.

I am interested in :

For the mail side of the company, I am thinking about an Ironport C150 and for web filtering, I am thinking about S350. The current company outgoing banwidth is 60 Mbit/s at peaks, but I want to be able to be able to continue to use it with traffic up to 200 Mbit/s, as we will maybe take some server in the company network in a few months.

Some questions :

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- Are they hard to setup and configure?

- Do they support many email languages?

- What is the price for both appliance, like around 5k each, 10k each?

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Feb 4, 2008

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How good is hot swapping in Linux? This was very hard to me to find out online. I am getting a 1U rack with a hot swap backplane and 2 SATA drives. I won't be using any commercial software with my setup.

How does redundant NIC work? This is new to me and am wondering how this is setup.

I think I can shop around NYC for a 1U slot for around $40 a month. I don't need a lot of transfer, but would like a decent pipe. The thought of 1Mbit sounds unattractive (transfer is around 100KBytes/s, right?). How much would 10Mbit cost? I found some quotes but they seem way too much (I could be wrong).

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