[K12OSN] Sanity check needed before rollout

["Terrell Prudé Jr."]

John Lucas wrote:
> On Tuesday 29 May 2007 22:29, Les Mikesell wrote:
>   
>> john wrote:
>>     
>>> Why does disk speed matter so much? Aren't most operations on a file
>>> server fairly small scale i/o once or twice a session i.e. opening a
>>> saved document, and writing a saved document.?
>>>       
>> The problem on a multi user machine is that every user wants the disk
>> head to be in a different place at the same time so seek time is often
>> more important than transfer rates. Consider what happens when everyone
>> is using a browser and every page and image each user loads is being
>> cached in their home directories.  Scsi disks/controllers can typically
>> take a bunch of commands at once and queue them up while IDE and most
>> SATA's can only do one comand at a time, waiting for CPU intervention at
>> each step.
>>
>>     
>
> The behavior ("Scsi disks/controllers can typically take a bunch of commands 
> at once and queue them up..."), is known as "elevator seeking" and is a huge 
> advantage of SCSI over SATA.
>
>   
I'd agree with the above; SCSI, if you can afford it, is always better.

However, if cost constraints are an issue (and I've seen plenty of
situations in which that's the case), I've actually used PATA for a
25-student lab.  Yes, EIDE.  One disk.  And nobody complained.  Granted,
it was an update from the Windows 98 that they were using, on Dell
Optiplex GX1's, so the speed increase by going with K12LTSP was heartily
welcomed, but if things were "slow", I would've heard about it (it's a
Microsoft shop).  Therefore, I'd suspect that a hardware RAID using SATA
would be just fine for 35 students.

--TP
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