Install question #1 - repository location
Bill Davidsen
davidsen at tmr.com
Wed Mar 12 23:11:58 UTC 2008
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
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