The below message is from OCLC:
OCLC services will be unavailable from 9:00 pm 4 June to noon 5 June (EDT US) approx. equivalent to SGP Time 9:00 am (5 June) to 12:00 midnight (6 June) for technology upgrades
As we have communicated in previous messages, OCLC is undertaking a significant investment in our technological infrastructure. We are evolving our data center strategy, upgrading equipment and infrastructure, and standardizing processes globally to increase service responsiveness. These investments will advance our service delivery for years to come so that together we can better meet library users’ increasing expectations.
This year-long effort is well underway. Much of the work is occurring behind the scenes. Some of these transitions require scheduled downtime for services.
As part of this initiative, all OCLC services will be unavailable from 9:00 pm Saturday, 4 June 2016, to 12:00 pm (noon) Sunday, 5 June 2016, Eastern Daylight Time (EDT) US (UTC -4) while we conduct data storage migrations.
While we scheduled this maintenance event to occur during a slower time for many of our member libraries, we understand that this event still impacts many. We apologize in advance for any disruption to you and your users.
As always, system activities and schedules can be viewed on our System Alerts page on the OCLC website. We will communicate through the System Alerts page if there are any changes or delays in completing this scheduled work, and we will also use this page to let you know when this work has been completed.
We are committed to the ongoing enhancement of our systems, infrastructure and processes, and we will continue to advance our delivery to you. Thank you for your continued support.