[cfarm-users] New M1 machine running Linux natively: gcc103

[Zach van Rijn]

On Sat, 2022-03-26 at 14:02 -0500, Zach van Rijn wrote:
> On Sun, 2022-03-13 at 10:34 -0500, Zach van Rijn via cfarm-
> users wrote:
> > ...
> > 
> > The /home directory is mounted from an external USB-C NVMe
> > drive because the internal storage is quite limited. Note
> > that it does run at USB2 speeds because there is not kernel
> > support *yet* for USB3. This will come in due course.
> 
> The USB2 performance has been tolerable, but is far from
> optimal:
> 
> 4194304000 bytes (4.2 GB, 3.9 GiB) copied, 69.7739 s, 60.1 MB/s

Some good news, in terms of reliability, for gcc103 users.

This USB adapter has been a major headache from an administrative
point of view. It requires constant supervision to catch issues
where the USB device resets and cannot be reconnected while the
system is online. So far, reboots are the only reliable fix.

Rebooting *several times a week* is disruptive to users, some of
whom wish to use the system for long-running (low CPU) tests.

It is not caused by a loose or too-long cable, however I will try
this setup again once the Asahi Linux project adds USB3 support
as it would greatly benefit performance and (maybe?) reliability.

I'm not convinced that the adapter is defective, either. But the
root cause is still to be determined. Something needs to change.


> Throughput could be doubled (1gbps) with networked storage in
> the short term but I'm not sure it would be a better user
> experience.

I've copied the data to a new and dedicated 1TB NVMe in another
server on the network. It is mounted via NFS and should be much
more reliable. If needed, backups can be performed easily, too.

(For the record, copying 127GB of data off this USB NVMe did not
trigger or reveal any disk issues; high load doesn't cause it).

+-------------------------+         +--------------------------+
| other server            |         | gcc103 (mac mini)        |
|                         |         |                          |
| [ 1TB NVMe for gcc103 ]<=== NFS ===>[ /home ] [ local disk ] |
|                         | (1gbps) |                  ^       |
+-------------------------+         +------------------|-------+
                                      (applications) <=/

I apologize for any increase in latency (over the network) but I
expect the performance to be generally improved except for maybe
a few specific scenarios. Please report any extreme slowdown.


> Note that /tmp is tmpfs and that typical compiles write to
> /tmp, so the performance is decent enough already.

This is still the case.


ZV