[Info-vax] Some I/O results

[Simon Clubley]

On 2023-11-10, Mark Berryman <mark at theberrymans.com> wrote:
>
> Now, how to get the data onto my VMS cluster?  The Alpha and Integrity 
> systems only have 1G Ethernet interfaces but the x86 system, as an ESXi 
> guest, has both 1G and 10G interfaces.
>

[snip]

>
> So, with SCP, the best I could manage was a copy around 5 MB/sec.  On 
> the other hand, a Mac to Mac copy - over the same 1G LAN - achieved over 
> 90 MB/sec, which is close to the maximum possible.
>

I assume the Mac to Mac copy is also using SCP ? It's not completely clear.

> With FTP, I could achieve around 14-15 MB/sec.
>
> My last option was NFS.  It managed better than 20 MB/sec.  It was also 
> much easier since I could NFS mount the source and then just use a copy 
> command to get the data and copy pre-allocates the destination file on 
> its own.
>

Are delayed ACKs turned on or off on the VMS systems ?

> Now here is the part that was surprising to me.  As mentioned, the Alpha 
> and Integrity systems were copying over a 1G Ethernet path whereas the 
> x86 system was using a 10G path (the Mac has both 1G and 10G 
> interfaces).  Using the exact same source and exact same I/O sizes, the 
> Alpha averaged 335 I/Os per second to its target disk, the Integrity 
> system managed just over 400 I/Os per second, but the x86 system 
> couldn't do any better than 279 I/Os per second - even on a link that 
> was 10 times faster.  (It also has a faster HBA than the other systems).
>

What type of disk ? Hard drive or SSD ?

It is possible the VM is causing some additional overhead ?

Anything in the Ethernet error and retry statistics from the usual tools ?

Simon.

-- 
Simon Clubley, clubley at remove_me.eisner.decus.org-Earth.UFP
Walking destinations on a map are further away than they appear.