Dell PE1550 with NAS back-end

Seth Mos knuffie at
Fri Jun 21 16:13:01 CDT 2002

At 15:46 21-6-2002 -0400, Chris Kirby wrote:
>Was wondering what kind of experiences people have had with running a
>web/mail server on a Dell PE1550 with NAS back-end storage? Is there a
>significant performance hit? The connection would be full duplex switched
>100mb/s using NFS.

You can serve a lot of pages over 100Mbit switched ethernet. It is quite 
common for some larger sites to make is easier to access.

>I don't imagine any noticeable hit on performance for SMTP/POP3 traffic but
>my main concern would be HTTP traffic. What sort of performance problems can
>I expect? Any other downfalls? I don't imagine my webservers would ever be
>pushing more than 5mb/s of Internet bandwidth during peak usage so I imagine
>having a 100mb/s NFS mount on the backend would suffice but I know there is
>some NFS overhead in opening and closing files each time there is an I/O
>request. Since a single HTTP pageview  can require many I/O requests for all
>of the different images needed, I am wondering if this would be any sort of

I don't think you have to worry about fetching your data from a NFS drive. 
It's transparrent to the OS and works just fine.

>The purpose is to make my web/mail servers redundant/failover capable. Easy
>enough to do except for the filesystem itself. Mostly concerned with the
>/home filesystem since this is where the webroot and maildir's are. Thought
>using a high quality back-end NFS SCSI RAID server with a /home mount would
>be cost effective but performance is my concern as well.

Some very large ISP's are doing this as well. If you are really concerned 
that you will run into a bottleneck you can always put a gige card in the 
NFS server and buy a cheap 3com baseline 6 port gige switch (Euro 700,-) 
and use that for that backend. But that has Overkill written all over it :-)

>Would it be better to use a distributed filesystem such as Coda to replicate
>the /home filesystem across many webservers instead of using NFS storage?

Sounds complicated for something so simple. I always stick to the KISS 

>Does not seem as cost effective though since a 500MB website would take up
>1500MB of disk space if I had 3 webservers to always replicate.

And the sync can be lost resulting in various hard to find but not so much 
fun problems.

>  A common
>filesystem seems to be the way to go. I know the NFS server would be a point
>of failure unless I had two of them but I am willing to accept this until I
>can afford two.

If all it is doing is serving NFS it will probably stay alive without 
problems. If you have a raid in the server and a hot swap powersupply as 
well as a UPS you catch most of the direct problems and it should not be 
such a problem to stay alive.


It might just be your lucky day, if you only knew.

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