I found a message on the (official) Apple forums that describes something like your problems:
https://discussions.apple.com/thread/7255967?start=0&tstart=0
It also mentions a solution:
"just downloaded the new raid manager and FW update, all seems fine now...."
I saw this post when I tried to figure out what was going on, but I could not find this RAID manager app on LACIE
website, seems like either they have dismissed this software altogether, or it was not meant to be used with Little Big Disk. New (or old) firmware is not available for my drive either. Besides, none of this was needed before.. it just worked...
What I would do is run the utility
Etrecheck once.
Here is the report (it is huge, my apologies for that):
Problem: No problem - just checking
Hardware Information:ⓘ
iMac (27-inch, Late 2013)
[Technical Specifications] -
[User Guide] -
[Warranty & Service]
iMac - model: iMac14,2
1 3.2 GHz Intel Core i5 CPU: 4-core
24 GB RAM Upgradeable -
[Instructions]
BANK 0/DIMM0
4 GB DDR3 1600 MHz ok
BANK 1/DIMM0
4 GB DDR3 1600 MHz ok
BANK 0/DIMM1
8 GB DDR3 1600 MHz ok
BANK 1/DIMM1
8 GB DDR3 1600 MHz ok
Bluetooth: Good - Handoff/Airdrop2 supported
Wireless: en1: 802.11 a/b/g/n/ac
Video Information:ⓘ
NVIDIA GeForce GT 755M - VRAM: 1024 MB
System Software:ⓘ
OS X El Capitan 10.11.2 (15C50) - Time since boot: about 16 hours
Disk Information:ⓘ
APPLE SSD SM0512F disk0 : (500.28 GB) (Solid State - TRIM: Yes)
EFI (disk0s1) <not mounted> : 210 MB
Macintosh HD (disk0s2) / : 499.42 GB (37.21 GB free)
Recovery HD (disk0s3) <not mounted> [Recovery]: 650 MB
ST2000LM003 HN-M201RAD disk1 : (2 TB) (Rotational)
EFI (disk1s1) <not mounted> : 210 MB
HDD1 (disk1s2) /Volumes/HDD1 : 2.00 TB (1.10 TB free)
ST2000LM003 HN-M201RAD disk2 : (2 TB) (Rotational)
EFI (disk2s1) <not mounted> : 210 MB
HDD2 (disk2s2) /Volumes/HDD2 : 2.00 TB (2.00 TB free)
ST1000LM024 HN-M101MBB disk5 : (1 TB) (Rotational)
BackUP2 (disk5s1) /Volumes/BackUP2 : 1.00 TB (479.93 GB free)
USB Information:ⓘ
Seagate Backup+ RD 1 TB
EFI (disk3s1) <not mounted> : 210 MB
Boot OS X (disk3s3) <not mounted> : 134 MB
BackUp1 (disk4) /Volumes/BackUp1 : 999.50 GB (622.39 GB free)
Encrypted AES-XTS Unlocked
Core Storage: disk3s2 999.86 GB Online
Apple Inc. BRCM20702 Hub
Apple Inc. Bluetooth USB Host Controller
Apple Inc. FaceTime HD Camera (Built-in)
Thunderbolt Information:ⓘ
Apple Inc. thunderbolt_bus
Seagate GoFlex Adapter Thunderbolt
LaCie Little Big Disk
Gatekeeper:ⓘ
Mac App Store and identified developers
Adware:ⓘ
Adware infection possible.[Scan for adware]
Kernel Extensions:ⓘ
/Applications/Parallels Desktop.app
[not loaded] com.parallels.kext.hypervisor (10.3.0 29227 - SDK 10.7)
[Support]
[not loaded] com.parallels.kext.netbridge (10.3.0 29227 - SDK 10.7)
[Support]
[not loaded] com.parallels.kext.usbconnect (10.3.0 29227 - SDK 10.7)
[Support]
[not loaded] com.parallels.kext.vnic (10.3.0 29227 - SDK 10.7)
[Support]
/Library/Extensions
[loaded] com.symantec.kext.SymAPComm (12.7.1f4 - SDK 10.8)
[Support]
[not loaded] com.symantec.kext.filesecurity (12.7f4 - SDK 10.8)
[Support]
[loaded] com.symantec.kext.fw (5.3.1f4 - SDK 10.8)
[Support]
[loaded] com.symantec.kext.internetSecurity (5.5f7 - SDK 10.8)
[Support]
[loaded] com.symantec.kext.ips (3.10.3f7 - SDK 10.8)
[Support]
[loaded] com.symantec.kext.pf (5.7.1f4 - SDK 10.8)
[Support]
/System/Library/Extensions
[not loaded] com.joshuawise.kexts.HoRNDIS (6 - SDK 10.0)
[Support]
[loaded] com.nvidia.CUDA (1.1.0)
[Support]
Launch Agents:ⓘ
[loaded] com.adobe.AAM.Updater-1.0.plist
[Support]
[loaded] com.adobe.ARMDCHelper.cc24aef4a1b90ed56a...plist
[Support]
[running] com.adobe.AdobeCreativeCloud.plist
[Support]
[running] com.bjango.istatmenusagent.plist
[Support]
[running] com.bjango.istatmenusnotifications.plist
[Support]
[running] com.bjango.istatmenusstatus.plist
[Support]
[loaded] com.google.keystone.agent.plist
[Support]
[loaded] com.nvidia.CUDASoftwareUpdate.plist
[Support]
[loaded] com.paragon.updater.plist
[Support]
[running] com.rosettastone.rosettastonedaemon.plist
[Support]
[loaded] com.symantec.errorreporter-periodicagent.plist
[Support]
[loaded] com.symantec.nis.application.plist
[Support]
[running] com.symantec.uiagent.application.plist
[Support]
[running] com.teamviewer.teamviewer.plist
[Support]
[running] com.teamviewer.teamviewer_desktop.plist
[Support]
[loaded] org.macosforge.xquartz.startx.plist
[Support]
Launch Daemons:ⓘ
[loaded] com.adobe.ARMDC.Communicator.plist
[Support]
[loaded] com.adobe.ARMDC.SMJobBlessHelper.plist
[Support]
[running] com.adobe.adobeupdatedaemon.plist
[Support]
[loaded] com.adobe.agsservice.plist
[Support]
[loaded] com.adobe.fpsaud.plist
[Support]
[running] com.bjango.istatmenusdaemon.plist
[Support]
[loaded] com.google.keystone.daemon.plist
[Support]
[loaded] com.microsoft.office.licensing.helper.plist
[Support]
[loaded] com.microsoft.office.licensingV2.helper.plist
[Support]
[loaded] com.nvidia.cuda.launcher.plist
[Support]
[loaded] com.oracle.java.JavaUpdateHelper.plist
[Support]
[running] com.symantec.deepsight-extractor.plist
[Support]
[loaded] com.symantec.errorreporter-periodic.plist
[Support]
[loaded] com.symantec.liveupdate.daemon.ondemand.plist
[Support]
[loaded] com.symantec.liveupdate.daemon.plist
[Support]
[failed] com.symantec.nav.migrateqtf.plist
[Support]
[running] com.symantec.sharedsettings.plist
[Support]
[running] com.symantec.symdaemon.plist
[Support]
[loaded] com.teamviewer.Helper.plist
[Support]
[running] com.teamviewer.teamviewer_service.plist
[Support]
[loaded] fi.polar.libpolar.plist
[Support]
[running] fi.polar.polard.plist
[Support]
User Launch Agents:ⓘ
[loaded] com.adobe.AAM.Updater-1.0.plist
[Support]
[failed] com.adobe.ARM.[...].plist
[Support][Details]
[loaded] com.jdibackup.ZipCloud.autostart.plist
[Support]
[loaded] com.jdibackup.ZipCloud.notify.plist
[Support]
User Login Items:ⓘ
iTunesHelper Application (/Applications/iTunes.app/Contents/MacOS/iTunesHelper.app)
Other Apps:ⓘ
[running] com.adobe.acc.AdobeDesktopService.180832.99682460-27F0-413D-92ED-5DC83448D47D
[running] com.adobe.accmac.180512
[running] com.apple.xpc.launchd.oneshot.0x10000018.EtreCheck
[loaded] com.simplexsolutionsinc.vpnguardhelperMac
Internet Plug-ins:ⓘ
Default Browser: Version: 601 - SDK 10.11
Flip4Mac WMV Plugin: Version: 3.3.1.3 - SDK 10.8
[Support]
AdobeAAMDetect: Version: 3.0.0.0 - SDK 10.9
[Support]
FlashPlayer-10.6: Version: 20.0.0.267 - SDK 10.6
[Support]
AdobePDFViewerNPAPI: Version: 15.010.20056 - SDK 10.8
[Support]
Silverlight: Version: 5.1.41105.0 - SDK 10.6
[Support]
QuickTime Plugin: Version: 7.7.
Flash Player: Version: 20.0.0.267 - SDK 10.6
[Support]
SharePointBrowserPlugin: Version: 14.5.5 - SDK 10.6
[Support]
AdobePDFViewer: Version: 15.010.20056 - SDK 10.8
[Support]
NortonInternetSecurityBF: Version: 1.11.0 - SDK 10.6
[Support]
MeetingJoinPlugin: Version: Unknown - SDK 10.2
[Support]
User internet Plug-ins:ⓘ
CitrixOnlineWebDeploymentPlugin: Version: 1.0.105
[Support]
Google Earth Web Plug-in: Version: 7.1
[Support]
Safari Extensions:ⓘ
Adblock Plus
Open in Internet Explorer
Norton Internet Security
3rd Party Preference Panes:ⓘ
CUDA Preferences
[Support]
Flash Player
[Support]
Flip4Mac WMV
[Support]
Norton\nQuickMenu
[Support]
Paragon NTFS for Mac ® OS X
[Support]
Perian
[Support]
Time Machine:ⓘ
Auto backup: YES
Volumes being backed up:
Macintosh HD: Disk size: 499.42 GB Disk used: 462.21 GB
Destinations:
Data [Network]
Total size: 2.00 TB
Total number of backups: 90
Oldest backup: 11/27/14, 8:25 AM
Last backup: 1/13/16, 1:31 PM
Size of backup disk: Excellent
Backup size 2.00 TB > (Disk size 499.42 GB X 3)
Top Processes by CPU:ⓘ
46% TeamViewer_Desktop
18% WindowServer
16% mdworker(20)
3% kernel_task
2% TeamViewer_Service
Top Processes by Memory:ⓘ
4.87 GB com.apple.WebKit.WebContent(28)
1.47 GB kernel_task
811 MB Safari(2)
737 MB com.apple.WebKit.Plugin.64(3)
516 MB SymDaemon
Virtual Memory Information:ⓘ
7.88 GB Free RAM
16.00 GB Used RAM (4.84 GB Cached)
2 MB Swap Used