captainfred Posted February 7, 2016 #1 Posted February 7, 2016 Hi, Is it normal for read only SSD cache to reset / go back to zero after a reboot? Seems to happen whatever version of XPEnoboot I use... DSM is 5.2 5592 Update 4. Hardware is HP MicroServer Gen8. Any fix for this? Thanks
b0wi Posted February 8, 2016 #2 Posted February 8, 2016 Yes, see this movie for more information: SSD Cache tip #1, don't kill the power! I was doing some electrical work on the house and shut off the breaker for the circuit I was working on. I didn't know that same breaker also ran power to my office and that shut off the Synology disk station and SSD cache. The SSD memory is of course non-volatile, but the ~1GB of system RAM used to index into that cache is volatile. So upon powering back up, I found the SSD cache usage had reset back to 0%. The cache itself was still there and working, just that all the previously cached data had been lost. I didn't lose any data off the DiskStation, no errors reported aside from the notification of an improper shut down. If you do a proper shut down, the cache index data is saved to the hard drives and is restored upon powering back up. Time to start designing a backup power system for that NAS.
brantje Posted February 8, 2016 #3 Posted February 8, 2016 But a reboot is a proper shutdown, so it makes no sense that the cache is cleared upon reboot. Posted via MyXpenology
captainfred Posted February 10, 2016 Author #4 Posted February 10, 2016 Exactly. It didn't lose power at all. I just rebooted from within DSM. I also tested it (after building the cache a bit) with a proper shutdown and powered it back on and it still cleared it. I assume then this isn't supposed to happen? Tested it with XPEnoboot 5.2-5592.2 and 5.2-5644.4.
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