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Archive for October, 2015

PACE clusters (mostly) ready for research (cont.)

Posted by on Tuesday, 27 October, 2015
Hello all,
I’d like to apologize again for the delays in getting back to an operational state after this maintenance period.  At this point we have most things stable, although there may have been a small number of jobs interrupted over the last couple of days.
About 85% of our compute nodes are available for jobs at this point, and we continue efforts to bring those back into service.
We’ve also worked out some performance issues with the new home directory file servers that primarily impacted users of the tcsh shell.
At this point, if you see any strange behavior (other than missing nodes! 😉 please do let us know via a request to pace-support@oit.gatech.edu.

PACE clusters (mostly) ready for research

Posted by on Friday, 23 October, 2015

Greetings,

We’ve made substantial progress getting through our activities, and are releasing jobs.  We still have a number of compute nodes that still need to be brought online, however all clusters have some amount of resources and are running jobs.  We will continue to work through these issues later today.  After sleep.

 

Major upgrade to DDN & a new scratch storage

All data migrated successfully to new front ends, additional disks have been added for upcoming scratch.  Substantial delays due to unanticipated long running processes to join compute nodes to the new GPFS cluster.  This work is still ongoing.  Benchmarking suggests a slight performance improvement for those of you with project directories in GPFS.

New PACE router and firewall hardware & additional core network capacity

successfully completed without incident.

Panasas scratch filesystem maintenance

successfully completed without incident.

Migration of home directories

successfully completed without incident.

Migration of /usr/local storage

successfully completed without incident.

Begin transition away from diskless compute nodes.

migrated approximately 100 compute nodes.  Some of these still have issues with GPFS, as above.

ONGOING: PACE quarterly maintenance – October ’15

Posted by on Thursday, 22 October, 2015

We’ve had some unexpected delays and challenges this go around.  The short version is that we will need to extend our maintenance activities into tomorrow.  We’ll do a rolling release to you as we can bring compute nodes online.

 

The long version:

The storage system that is responsible for /usr/local and our virtual machine infrastructure experienced a hardware failure that caused us a significant amount of lost time.  Some PACE staff have spent 40 of the last 48 hours on site in order to try and make corrections.  We were already planning on transitioning /usr/local off of this storage and had alternate storage in place.  Likewise for the virtual machines, although our plan was to live-migrate those after maintenance activities were complete.  The good news is that we don’t have data loss, the bad news is that we’ve had to accelerate the virtual machine migration, resulting in additional unplanned effort.

Also, the DDN work is taking far longer than expected.  Part of this work required us to remove all nodes from the GPFS filesystem and add them back in again.  Current estimates to bring everything back to full production range from an additional 12 to 24 hours.  This means between 10am and 10pm tomorrow before we have everything back up.  As mentioned above, we will make things available as soon as we can.  Pragmatically, that means that clusters will initially be available at reduced capacity.  Look for another post here when we start enabling logins again.

UNDERWAY: PACE quarterly maintenance – October ’15

Posted by on Tuesday, 20 October, 2015

Our maintenance activities are now underway.  All PACE clusters are down.  Please watch this space for updates.

 

For details on work to be completed, please see our previous posts, here.

PACE quarterly maintenance – October ’15

Posted by on Tuesday, 6 October, 2015

Greetings,

The PACE team is preparing for our quarterly maintenance that will occur, Tuesday, October 20 and Wednesday, October 21. We have a number of activities scheduled that should provide positive improvements across the board.

  • Major upgrade to DDN & a new scratch storage. This is the flagship activity in this maintenance period. We have negotiated a no-cost upgrade of the DDN infrastructure to add additional performance and ability to expand our DDN storage. In particular, we will be adding a dedicated set of drives to serve as a replacement for our aging Panasas scratch storage. This should more than double the storage available in the scratch filesystem available to campus and provide a substantial performance increase as well. We’ve heard your concerns about scratch, and are doing our best to make improvements in this area.

** NO USERS WILL BE MIGRATED DURING THE MAINTENANCE PERIOD **

After the maintenance period, we will begin migrating users to the new scratch storage. This will be a lengthy process, with some user actions and coordination required. We will do our best to minimize the impact of the migration. We are targeting our January maintenance to retire the Panasas storage, as the service contracts expire at the end of December.

  • New PACE router and firewall hardware. This replaces the stalwart router and firewalls that have been the core of our network for the better part of 10 years. Additional redundancy will provide increased protection from datacenter failures and increased firewall capability should result in increased file transfer speed in and out of PACE. Our dual 10-gigabit link to the rest of campus remains unchanged, but the new firewalls should allow us to actually use more of that capacity.
  • Additional core network capacity. Upgrades to 40-gigabit switching in the core of our network provides additional capacity and allows 40-gigabit upgrades to various infrastructure services.
  • Panasas scratch filesystem maintenance. We need to do a filesystem check on a couple of the scratch storage volumes. This should be an innocuous operation, but may take a long time to complete.
  • Migration of home directories. We are replacing the aging servers providing home directories with new high-availability NFS storage. This should be a transparent change. Home directory quotas will not change.
  • Migration of /usr/local storage. We are migrating the location of the /usr/local software repository to a new storage device as the company from whom we purchased the old storage has gone out of business. This should also be a transparent change.
  • Begin transition away from diskless compute nodes. Many of our older nodes currently operate without any local storage. Using old, but tested, disks reclaimed from retired equipment, we will be transitioning as many as possible away from a diskless mode of operation. This is the beginning of a long-running project to fully transition away from diskless nodes.  Apart from more predictable performance of these nodes, this should also be a transparent change.