10 Replies Latest reply on Dec 21, 2012 1:52 PM by rseiler

    Uncorrectable Error Count - Intel 520 SSD



      I was surprised to find out how big the raw value of Uncorrectable Error Count for my drive is: 220147178. The rest of the attributes in SMART seem to have normal values. I've checked the value both in Windows 7 64-bit using Intel SSD Toolbox (3.0.2) and GNU/Linux using smartmontools. I've also noticed it grows quite rapidly when using the ssd.


      According to the documentation Intel 520 SSD Product Spec:

      The raw value shows the count of errors that could not be recovered using Error Correction Code (ECC).
      Full Diagnostic Scan in Intel SSD Toolbox passes without errors. Furthermore in linux I have successfully copied many big files (checked their md5sums).
      The funny thing is that after running the Full Diagnostic Scan the raw value is smaller: 169588940 (overflow?).
      I also found some screenshots from anandtech's review of Intel 520 SSD and his Uncorrectable Error Count raw value was 0.
      Motherboard: Gigabyte P35-DS3L (yes, SATA2...)
      Any ideas what's going on?


      Thanks in advance!

        • 1. Re: Uncorrectable Error Count - Intel 520 SSD

          My 520 has a similar value for uncorrectable Error Count, which is a Raw value so cannot be interpreted literally by itself. In another article on Anandtech's site, about using Intel SSDs in enterprise applications, he discusses using tools to reset various SMART data values. Perhaps he reset it. Did you secure erase your 520? I fooled around with mine for a week or so, and then did a SE and installed Windows. Just looking for similar usage between us.


          My 520 is fine so far, just installed Win 7 on it yesterday, using it now but not done with the installation (a pre-SP1 copy of Win 7, ugh!!) yet. Notice that your Power-On Hours Count raw value is a pretty crazy value, but obviously just not processed correctly. I must check my other Intel and other SSDs, that are spread across three PCs, if they even have that value.


          I'm not worried about it right now. We'll need more information about that SMART value before coming to any conclusions. That value is no doubt from the SandForce controller. Yet another thing to do, more study...

          • 2. Re: Uncorrectable Error Count - Intel 520 SSD

            No, I haven't done any SEs.


            The funny thing is that today my raw value of the Uncorrectable Error Count attribute is 0. The only things that I did (in order): boot Windows, reformat the ssd as ntfs, run Intel SSD Toolbox (Full Diagnostic), reboot. Checked the readout in both Windows and GNU/Linux.
            The Power-On Hours Count raw value is still incorrect considering the description in the spec:
            • 3. Re: Uncorrectable Error Count - Intel 520 SSD

              I have the same error count - how ever when start Windows it goes back to zero.

              Like the same 'Unsafe shutdown count', I take its nothing to worry about? At least other's have noticed this too...


              As i said in another post 'problems with 520' I am extremely pleased with the performance of this SSD.

              • 4. Re: Uncorrectable Error Count - Intel 520 SSD

                Yes, you're totally right. I have rechecked the raw value and it is again > 0. I'm sure I have checked that the value was 0 after doing some reads/writes, so this must occur only after a longer uptime (and a reset needs booting and then turning off Windows?). Maybe this is also connected with the unsafe shutdown values noted in the other thread i.e. when Windows unsafely unmounts the disks only then is the Uncorrectable Error Count zeroed (pure guess).

                • 5. Re: Uncorrectable Error Count - Intel 520 SSD

                  I found some information that if true, would possibly explain why the UEC count is wrong or a strange value (if it actually is wrong or strange.)


                  As we know, the 520 is the first Intel SSD to use the SandForce 2281 SSD controller. You may also know that Intel has been working with SandForce (now LSI) for over a year to verify the 520's dependability, and implement some proprietary (to Intel) 2281 firmware changes or fixes. A recent review of the 520 at XbitLabs mentioned that one area of the firmware that Intel changed was in it's error correction.


                  To quote from the XbitLabs 520 review: "The key firmware feature – compression of data written to flash memory –  has of course remained intact but some algorithms (for example, for  error correction) have been revised especially for the Intel solution."


                  Beyond that, regarding what the raw value for UEC should be, or normally is in a correctly functioning 520, I really don't know. I've never owned a SSD with the 2281 controller besides the 520, so I have no experience with the UEC SMART attribute on other SSDs using the 2281 controller. I know nothing about the UEC attribute, so I'm in no position to make any comments about it. IMO, we need information about it before we can have any meaningful discussion about it.


                  I installed Windows 7 on my 520 earlier this week, and have restarted, shutdown, and rebooted that PC many times, and my UEC value remains non-zero. I'll keep checking it, but I can't correlate the UEC value with anything right now.

                  • 6. Re: Uncorrectable Error Count - Intel 520 SSD

                    interesting reading .. thanks parsec

                    • 7. Re: Uncorrectable Error Count - Intel 520 SSD

                      I have the exact same problems. please anyone help me !!

                      • 8. Re: Uncorrectable Error Count - Intel 520 SSD

                        It's really not a problem IMO, my 520's are working fine, including pairs in RAID 0. I noticed that value will reset to 0 after a reboot or cold start. My 520's seemed to get a non-zero value when they were newly installed, and that subsided over time and reboots. A pair in RAID 0 would both have a non-zero UEC value, although not equivalent values. Quite a coincidence that both SSDs would have the same issue if it was a drive issue. It may be a side affect of something else occurring, like a driver having a problem, or anything among the thousands of things happening on a PC.


                        Calin, are you having problems with your PC or your 520?


                        IMO, we should keep in mind how complex PC systems are, and there is so much that the average or way above average user is not aware of or understands, which certainly includes myself.

                        • 9. Re: Uncorrectable Error Count - Intel 520 SSD

                          Well, i have no problems in terms of speed ( ATTO benchmark benches the ssd proper). The uncorrectable error count is reset to 0 after the PC is rebooted, but after some minutes the raw values rises again to huge numbers. I've talked to a few people with the same SSD, and they have the same problems. So i guess this is a Intel "problem" or their custom firmware could not be read by software proper.