Update, May 28th: The Lab reports this work is now complete.
On Tuesday May 27th, Linden Lab gave warning that there will be a period of scheduled maintenance on Wednesday May 28th which will see log-ins suspended for around one hour, from approximately 06:00 SLT.
The notice, posted to the Second Life Grid Status Page reads in full:
The Second Life Service will be closed for logins for approximately one hour on Wednesday, May 28 beginning at 6am PDT.
Residents in world will not be logged out, but may experience loss of supporting services such as search and inventory. New logins will not be accepted, and Residents in world should not attempt to transfer or manipulate L$ or valuable (no-copy) assets until the ALL CLEAR is given.
As always, if the scope or the schedule of the work changes, we will update this post.
Please check with the Grid Status page for updates nearer the time of the maintenance.
The maintenance work is most likely the work planned for Thursday May 22nd, which had to be postponed as a result of significant issues in Second Life services encountered on Tuesday May 20th. Among other things, those issues resulted in the server-side deployments for that day being curtailed, which directly impacted planned activities for the rest of the week.
Assuming the work is the same as that originally planned for May 22nd, it would appear to be focusing on database hardware, with the result that sims should have slightly faster access time after the work has been completed, although the emphasis has been that if this is the case, it will not be major or noticeable.
Following the problems encountered in week 21, Landon Linden issued a blog post explaining some of the causes of recent problems within the platform, which is recommended reading for those who haven’t yet done so.