https://devzone.nordicsemi.com/f/nordic-q-a/29299/fds-leaves-a-hole-in-flashHi, I have seen some curious behavior with the FDS module. I&#39;m using nRF5SDK 14.2.0 with s140_nrf52840_5.0.0-2.alpha, with FreeRTOS. In short: In some cases it seems that doing writes/updates that collide somehow will leave &quot;holes&quot; (0xFFFFFFFF whereen-USTelligent Community 13Tue, 09 Jan 2018 14:32:15 GMThttps://devzone.nordicsemi.com/thread/116549?ContentTypeID=1Tue, 09 Jan 2018 14:32:15 GMT137ad170-7792-4731-bb38-c0d22fbe4515:79f17653-5710-4a49-900a-6545204a9348J&#248;rgen Holmefjord<p>I can see the confusion, but this symbol only ensures that the library works with different users, like peer_manager and application, it does not ensure thread safe operations. We are looking into the possibility of making it thread safe, but this will require a very large amount of critical region sections, which will disable interrupts. I can&#39;t say anything about if or when this will happen.</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/116550?ContentTypeID=1Tue, 09 Jan 2018 13:26:48 GMT137ad170-7792-4731-bb38-c0d22fbe4515:90321eba-197e-4eef-aaf2-0f789100c43d&#216;yvind<p>Thanks, I see. I guess I got confused by the inclusion of FDS_THREADS definition. Also, does the word &quot;currently&quot; indicate that this will be made thread safe soon?</p> <p>Anyway, this seems to be stable enough for me with my mentioned workaround.</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/116548?ContentTypeID=1Tue, 09 Jan 2018 13:11:29 GMT137ad170-7792-4731-bb38-c0d22fbe4515:063288f7-02ec-4150-934c-73866845560dJ&#248;rgen Holmefjord<p>Hi,</p> <p>Unfortunately, Flash storage, which FDS build on is <a href="https://infocenter.nordicsemi.com/topic/com.nordic.infocenter.sdk5.v14.2.0/lib_fstorage.html?cp=4_0_0_3_51">currently not thread safe</a>.</p> <p>Best regards,</p> <p>Jørgen</p><div style="clear:both;"></div>