Dreamhost PS MySQL


#1

*For MySQL, CPU time is much less important than RAM and disk speed (MySQL PS uses local, raided, high-speed SAS drives).
Since it is not a potential bottleneck, on MySQL PS CPU time is approximate… though still proportional to your RAM level.

Can anyone elaborate on that? Is it saying that unless you’re performing pretty hardcore queries (multiple joins, sub-selects, etc) you’re not going to need it?

What your experiences with the MySQL servers - are they quite busy?

Also, I’ve had issues on Joomla sites on my account, where MySQL is unavailable. Could have been DNS related though (it was last week). But say it wasn’t DNS related, do you reckon using the VS version of mysql would have better reliability.

Cheers
GLOB


#2

[quote]*For MySQL, CPU time is much less important than RAM and disk speed (MySQL PS uses local, raided, high-speed SAS drives).
Since it is not a potential bottleneck, on MySQL PS CPU time is approximate… though still proportional to your RAM level.

Can anyone elaborate on that? Is it saying that unless you’re performing pretty hardcore queries (multiple joins, sub-selects, etc) you’re not going to need it?[/quote]
What they’re saying is that most of the time, memory is the bottleneck to good database performance. So pay attention to the amount of memory that you think your application queries will need, not the CPU time they require.

I think this is dependent on both your own use and the vagaries of your shared hosting neighbors. I depend on caching of dynamic content as static pages for my performance so I don’t do a lot of hand-wringing over database performance.

DNS issues, if they affect your webserver, will affect your application. That said, strictly speaking since you get a local running copy of MySQL, DNS problems won’t affect your application’s ability to access the database. The fact that MySQL is local will also improve performance.

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#3

Hi Lensman,

Thanks for the info.

So regarding shared mysql, are there many servers (same as with the web) and you may/may not be on one with busy neighbours? or is it all just one big cluster?

Static cache is a great approach. I’m using Joomla caching now, but nothing beats plain HTML for performance.

I like the sound of having a local instance of mysql. Will have to look into it.

Thanks again


#4

Hi GLOB,

Actually, upon studying the option, I’m not sure that the MySQL is local to your web server. I’ll have to check with support and report back.

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#5

Yup, sales confirmed that the PS MySQL servers are still remote. Apologies for the earlier misinformation.

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#6

I’ve had DH report that my sites were down because of DNS issues affecting the MySQL server, and they had to manually reboot their DNS. So I’d pay a small premium to have MySQL hosted on “my own” PS as localhost. Seems less likely to be down when I need it.

Jack.
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#7

I wonder if PS MySQL servers get their own dedicated IP too? Maybe access MySQL using the IP and not DNS name. Maybe it wouldn’t work though very well.


#8

I doubt that DH may only gives dynamic IP to PS MySQL

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#9

This goes to the question of how DreamHost’s MySQL is currently set up. There are really two questions:

  1. The PHP management interface.
  2. The actual database connection on port 3306 (or whatever port it is configured to).

You’re getting a virtual host, so I think it’s reasonable to presume that the host would get an IP address. The question then becomes whether you could connect directly to that IP address. For the management interface, you could not because you’d still create sql hosts for phpMyAdmin and you’d need hostnames in order for the apache on your host to “do the right thing”.

For direct database connections, I have to admit that I don’t know how the MySQL configuration DreamHost is set up. The IP address of my phpMyAdmin hosts are different from the address of the MySQL server listed in the admin screen.

At any rate, DreamHost has competent system administrators so I’m sure they’ve taken the DNS factor into account and have optimized for administration, reliability, and performance. I’d guess that the configuration would be similar to what exists now for shared MySQL hosting, but that the back end data server would run on a DreamHost private server (a MySQL one with local raided disk).

One experiment you could try is to connect directly to your mysql database using the IP address of either one of your phpMyAdmin hostnames or the IP address of your database server itself. If you do try this out, please report back!

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#10

Thanks for the clarification.
I’d agree with jhobbs - localhost mysql would be a big help… I keep having Joomla downtime and it’s just because of slow mysql connections (yes i know this is cheap hosting :slight_smile: )


#11

I’m not disagreeing that localhost mysql could be a good thing (and I’m pretty sure I actually brought up the subject by mistake in an earlier post), but I do wonder in which cases it’s actually significantly beneficial.

I’ve been writing SQL database applications for 20 years and we’ve never had the database run on the local host of the application - web application or not. This has been a performance bottleneck exactly never for me.

I don’t doubt that there are cases where a local database is beneficial. I just wonder what applications would benefit from this architecture. I’ve found that most performance problems from the database are a result of the time to actually execute the query, not the latency of network or transmit time of the results.

Now if you’re talking just about the unreliability of resolving the hostname of a remote server, there are solutions to that problem that don’t involve hosting the database on the web server.

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#12

Yeah, I would say that most of the time MySQL over the network is adding almost no overhead. It would be one thing when you are contacting a DB which is over the sea and 200ms away but not when you are contacting it in <1ms latency over LAN.