Yandex’s data centre in Sasovo, in Russia’s Ryazan region, was shut down overnight after a fire. Yandex says its core services, Search included, are running normally. That claim has a caveat attached, and the Yandex Cloud customers sitting in the affected zone are the ones who’ll notice it first.
The company’s first statement, quoted by Interfax on Thursday morning, was carefully worded: “an incident has occurred at the data centre in Sasovo that affected part of the infrastructure. The situation on site is now under control, there are no casualties. The team is dealing with the consequences and restoring the affected services.” The same report says the data centre’s operation has been fully stopped. Yandex insists its main services are working as normal, “although some of them may be unavailable for users”. RIA Novosti carried the same line from the press service: “the data centre’s work has been completely stopped, part of Yandex’s services may be unavailable to users”.
Later statements were less vague. A MiraNews report quotes the press service as saying the fire broke out “as a result of a UAV attack”. Reuters, via The Straits Times, reports that the company said drones hit the site, calls it the first major attack on a Russian data hub, and repeats Yandex’s line that core consumer services were not affected.
What actually went down
Yandex Search is still answering queries. The damage so far is in Yandex Cloud. According to the Kyiv Independent, Yandex Cloud acknowledged power-supply problems in its ru-central1-b availability zone, with disruption starting at around 1:31am. The company warned the outage could affect other parts of its cloud network and told customers to move workloads elsewhere. Censor.net lists what customers in that zone lost or saw degraded: compute, networking, storage, managed databases, Kubernetes and other cloud services.
Sasovo isn’t a minor site. Interfax says it opened in 2014 in part of the old Sasta machine-tool plant, and that Yandex laid several fibre lines to Moscow to tie it into its network. The Kyiv Independent says Yandex describes it as its largest data centre. KP.ua quotes Ryazan governor Pavel Malkov saying in 2022 that it housed tens of thousands of servers handling requests across Yandex services, and puts its capacity at around 12 MW. One more detail matters: the Kyiv Independent also notes that public outage monitors showed no sign of a widespread outage across Yandex’s main consumer services.
Why SEOs should care, even if Search held up
Yandex designed its systems to survive losing a site, and that’s mostly why Search didn’t fall over. Earlier this week we covered the open-sourcing of YTsaurus Flow, the streaming engine behind Yandex’s ad models. Its documentation describes a typical three-data-centre deployment so processing continues if one site goes down. Thursday was a real test of that design.
The people who should check their dashboards today aren’t searchers. They’re the Russian site owners who host on Yandex Cloud. If your site, CDN origin or database sits in ru-central1-b and went down overnight, every crawler got errors while it was dark, Yandex’s own robot included. My checklist:
- Crawl stats in Yandex Webmaster. Look for a spike in 5xx responses or timeouts from early Thursday. Once you’re stable, request recrawls of your important URLs rather than waiting for the robot to come back on its own.
- Metrika and analytics gaps. If your tag or server-side collection ran through the affected zone, expect a hole in Thursday’s data. Annotate it now before someone reads it as a ranking drop next month.
- Ads and feeds. Merchant feeds, landing pages and tracking endpoints hosted in that zone may have served errors to Yandex Direct and Market as well as to users.
Don’t read a dip in Thursday’s Yandex traffic as an algorithm update until you’ve ruled this out. The Yandex board on SearchEngines.guru already has a thread titled, roughly, “One of Yandex’s data centres has experienced some bad evil”. Expect more threads blaming Yandex for traffic wobbles this week.
The bigger picture
Yandex is putting enormous amounts of compute into Alice AI. It is training foundation models from scratch, and Alice answers are now a mass surface in Search. That kind of AI search needs a lot of servers in a few very large buildings. MiraNews, citing AiF and the regional emergencies ministry, says a drone-attack warning was in force across Ryazan from 23:48 to 02:06. Reuters notes the attack followed a wave of Russian strikes on Ukrainian data centres in recent weeks.
Whatever you think of the wider context, the operational lesson for anyone running sites in the Russian market is plain. A single cloud zone counts as a single point of failure. Yandex built its own stack for multiple data centres. Most of the sites it indexes haven’t. I’ll update our Yandex News coverage if the company says anything about the impact on crawling, Webmaster or Metrika.