[LON-CAPA-admin] RE: access server requirements

[Guy Albertelli II]

Hi Martin,

> On Thu, Oct 03, 2002 at 01:11:44PM -0400, Ron Fox wrote:
> > 
> > I may be completely wrong but it seems to me the specs you give are
> > probably more like what you'd like a library server to be.  The
> > access servers may not need quite the oomph.  
> > RF
> 
> On Wed, Oct 02, 2002 at 15:49:42 -0700, Ray Batchelor wrote:
> > > We are currently considering 2 access machines with:  dual 2.4GHz cpu;
> > > 4GB mem; Raid 1 with 2 SCSI disks (mirroring...not sure whether this
> > > is necessary but suspect that the increased cost might be relatively
> > > small compared to potential benefit).                               
>
> My impression was that the main difference between the requirements for
> access and library servers is the disk performance: whereas for
> library servers you want something like RAID 5 you may get away with
> cheaper low performance disk system on access servers.
> Is this correct?

I would say so.
 
> My impression also was that it is the load of the particular machine
> (access or library server) that determines whether that machine is used
> or not. Correct? Thus, by installing access servers with high cpu
> performance you can actually decrease the load on the library server,
> because the access servers can handle more requests.
> Thus, high-performance cpus on access servers would make sense, right?

Correct, in fact we generally set it up here so that the access
servers are the only ones the students login to.

> What kind of disk performance do access servers require? Do I need to
> by SCSI disk or are IDE disks sufficent?

Modern IDE is really quite nice so I woudn't think they would cause
 any problems.

> How large do those disks have to be?

Access servers only store copies of the resources, so a quarter of the
size of you library server will always be more than enough.

> I am also wondering whether we should invest in high-availability
> servers from one of the "big" companies (IBM, Dell, etc.) or whether
> we can get away with a "noname" product for almost half the price.
> Is it correct for LON-CAPA that if one of the access server crashes
> the other one and the library server will take over the load seamlessly
> without noticeble effect for the users? 

Only the users currently working on the crashed machine would notice.
And yes properly configured the others should just take over.

> In that case we obviously would be better off with a noname product
> because we could buy twice as many access servers.

I would agree.
-- 
guy at albertelli.com          BM: n^20 t20 z20 qS 
Guy Albertelli -7-7-9-  O-
    Today I will rely on the language of love and understanding. 
    If that doesn't work, I'll go back to intimidation and fear.