Install question #1 - repository location

[Bill Davidsen]

Kam Leo wrote:
> On Tue, Mar 11, 2008 at 12:40 PM, Bill Davidsen <davidsen at tmr.com> wrote:
>> I'm trying to find the best location for a repository to do FC8
>>  installs. My first two trials were direct from DVD and NFS mounted. The
>>  NFS mount showed that the max data rate to the new machine was only
>>  about 12MB/s, so transfer rate isn't an issue, it's Gbit connection.
>>  Therefore, I suspect that seek time may be an issue, I'm wondering if
>>  people have compared putting the repository on a USB stick instead of
>>  network.
>>
>>  --
>>  Bill Davidsen <davidsen at tmr.com>
> 
> Drive seek times are in the range of 8 - 20 ms. Your NFS server's hard
> drive has 8 - 32 MB of cache. The server's I/O driver provides
> additional caching/buffering. Data is being accessed sequentially,
> i.e. beginning of file to end of file. Unless the server has a heavy
> I/O workload the disk access/seek times should be completely masked by
> the buffering.
> 
I don't see how you get that, for many small RPMs the transfer time 
would be no larger than the disk seek time, even if only 100Mbit or so 
is actually used.

> How is the server drive's seek time a limiting factor when your target
> system also has to store that same data on its own drive?
> 
> Flash drive install will be faster because you eliminate the
> networking protocol overhead.
> 
That was the unresolved issue. Gbit networking is faster than the USB 
bus, but I never saw any indication that the transfer rates over the 
network were taking advantage of that, they barely would reach the limit 
of 100Mbit. That's why I was wondering if the faster seek on a flash 
would be more important than the slower transfer rate.

Note: I was really surprised at how many packages are small, on the DVD 
25% are <50k.

-- 
Bill Davidsen <davidsen at tmr.com>
   "We have more to fear from the bungling of the incompetent than from
the machinations of the wicked."  - from Slashdot