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Data Storage Power Businesses IT

Enterprise SSDs, Powered Off, Potentially Lose Data In a Week 184

New submitter Mal-2 writes with a selection from IB Times of special interest for anyone replacing hard disks with solid state drives: The standards body for the microelectronics industry has found that Solid State Drives (SSD) can start to lose their data and become corrupted if they are left without power for as little as a week. ... According to a recent presentation (PDF) by Seagate's Alvin Cox, who is also chairman of the Joint Electron Device Engineering Council (JEDEC), the period of time that data will be retained on an SSD is halved for every 5 degrees Celsius (9 degrees Fahrenheit) rise in temperature in the area where the SSD is stored. If you have switched to SSD for either personal or business use, do you follow the recommendation here that spinning-disk media be used as backup as well?
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Enterprise SSDs, Powered Off, Potentially Lose Data In a Week

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  • I call BS (Score:3, Insightful)

    by Anonymous Coward on Sunday May 10, 2015 @05:06AM (#49657073)
    If the contents are lost in a week, we're probably talking about capacitor-backed SSDs that use some other technology than flash memory. Yes, it would be insane to use flash memory for archival purposes as well, but it still should easily retain its contents for at least a decade. When powered on, this problem does not exist as normally the controller slowly walks through the flash refreshing it.
    • Re: (Score:3, Insightful)

      by luther349 ( 645380 )
      probably and no data center is going to not have power for a week and always have non flash based memory backups even if they did.
    • Re:I call BS (Score:5, Informative)

      by gweihir ( 88907 ) on Sunday May 10, 2015 @05:51AM (#49657173)

      The statements are actually completely accurate, but a bit misleading. First, this is about what JEDEC requires, not what actual SSDs deliver. Second, this is when SSDs are stored in idle at 55C. And third the JEDEC requirements for minimum off-time data-retention are only 3 months @40C for enterprise-grade SSDs and only 12 months for consumer SSDs at 30C. These are kind of on the low side, although I have lost some OCZ drives that were off for just about a year. (Never buying their trash again...)

      That said, anybody conversant with SSD technology knows that SSDs are unsuitable for offline data storage as data obviously has potentially far shorter lifetimes than on magnetic disks, which in turn again have far shorter data lifetime than archival-grade tape. These is absolutely no surprise here for anybody that bothered to find out what the facts are. Of course, there are always those that expect every storage tech to keep data forever, and those dumb enough to have no or unverified backups and those often on media not suitable for long-term storage. Ignoring reality comes at a price.

      My personal solution is mixed HDD/SSD Raid1 and, of course, regular backups.

      • by Kjella ( 173770 )

        My personal solution is mixed HDD/SSD Raid1

        Uhh... doesn't that mean that the RAID controller has to wait for the HDD on every read/write to verify it's the same as on the SSD, so effectively you get HDD performance?

        • Re:I call BS (Score:5, Informative)

          by Spazmania ( 174582 ) on Sunday May 10, 2015 @06:49AM (#49657303) Homepage

          Every write, not every read. Reads are satisfied as soon as either drive returns the data. And if the raid controller has a battery or supercap so it can cache writes, you'll almost never notice the difference.

          • by dfghjk ( 711126 )

            "Reads are satisfied as soon as either drive returns the data. And if the raid controller has a battery or supercap so it can cache writes, you'll almost never notice the difference."

            RAID controllers do not launch reads on all involved drives. That would be stupid.

            Implementing battery backed write back cache on an array that uses SSD would be similarly stupid.

            RAID 1 with mixed SSD/HDD is the worst of both worlds further complicated by people who don't understand it.

            • by drsmithy ( 35869 )

              RAID controllers do not launch reads on all involved drives. That would be stupid.

              ?

              For a RAID1, most RAID controllers (and software RAID implementations) will absolutely read from all devices so as to service the read ASAP.

              For distributed parity forms of RAID, you inherently have to read from all devices.

              For dedicated parity disk forms of RAID, you have to read from all devices except the parity device.

              I've never tried a mixed RAID1 of SSD and magnetic disk, but with a large enough write cache the theory se

              • by tepples ( 727027 )

                For dedicated parity disk forms of RAID, you have to read from all devices except the parity device.

                I think the idea is to make a dedicated parity disk RAID with one data SSD and one parity HDD.

              • For a RAID1, most RAID controllers (and software RAID implementations) will absolutely read from all devices so as to service the read ASAP.

                For distributed parity forms of RAID, you inherently have to read from all devices.

                The problem is guaranteed with distributed parity raid; the controller will have to wait for the slowest disk to complete the read. Both reads and writes will be limited to mechanical disk performance levels.

                With a RAID1 mirror set, you can get a performance improvement on reads since the SSD would presumably service all of them. Writes will still be delayed by the mechanical drive(s).

                In addition, most RAID controllers do not support mixing drive types. Most of them don't even recommend mixing drive speeds

            • Implementing battery backed write back cache on an array that uses SSD would be similarly stupid.

              How do you figure? Write to ram is a whole lot faster than write to flash, especially if the flash block has to erase first.

            • by unrtst ( 777550 )

              RAID controllers do not launch reads on all involved drives. That would be stupid.

              I think you mean that they do not launch a read request for the same chunk of data on all drives in a raid mirror. That would be accurate. However, they usually will read from both drives (read chunk 1 from drive A, read chunk 2 from drive B... doing so in parrallel can significantly increase read performance using a mirror).

              RAID 1 with mixed SSD/HDD is the worst of both worlds further complicated by people who don't understand it.

              Do you mean people like you?
              Look up "md raid write-mostly", or try this page (one of many found): http://tansi.info/hybrid/ [tansi.info]
              That setup is for a linux software RAID 1 mirror with one side

          • by Kjella ( 173770 )

            Every write, not every read. Reads are satisfied as soon as either drive returns the data. And if the raid controller has a battery or supercap so it can cache writes, you'll almost never notice the difference.

            Ah, I thought RAID1 would warn you somehow of bit flips which I assume would be the way heat-deteriorated storage would show up. Guess it won't, you'll need ZFS or something like that.

            • Thats very dependant on whose implementation of raid 1. I've seen everything from read from one drive, stripe reads, and read from both and compare. Linux will actually let you choose from among some of those options.

              ZFS and btrfs add a crc for a group of blocks and and detect which drive has the bad data, correct that and tract that it happened.

        • use ZFS l2arc/zil or flashcache/dm-cache to get a happy medium.

          • by thogard ( 43403 )

            I've been thinking about getting a bunch of cheap usb sticks and building a zfs pool out of them with some redundancy and then using that for a zfs pool for a usenet spool just to see what can go wrong. If anything can abuse a disk its usenet.

            • The modern day floppy-raid. [wired.com]

            • I've done this, experimentally, using not-super-cheap 128GiB patriot and hyper-x usb3 sticks.

              For a USENET load, performance will depend on whether your incoming feed is predominantly batched, streaming, or effectively random -- small writes bother these devices individually, and aggregating them into a pool works best if you can maximize write size. One way to do that is to use a wide stripe (e.g. zpool create foo raidz stick0 stick1 stick2 stick3 stick4 ...), which works well if your load is mainly batch

              • Ah, cannot ETA, so: decent USB 3 sticks make *excellent* l2arc devices in front of spinny disk pools. They can often deliver a thousand or two IOPS each with a warm l2arc, and that would otherwise mean disk seeks. I use them regularly.

                (The downside is that in almost all cases l2arc is non-persistent across reboots, crashes and pool import/export, and can take a long time to heat up so that a good chunk of seeks are being absorbed by them, so you're limited by the IOPS of the storage vdevs and the size

      • Re:I call BS (Score:5, Informative)

        by DarkTempes ( 822722 ) on Sunday May 10, 2015 @06:53AM (#49657311)

        I might be wrong but isn't it also when the SSD is stored at 55C AFTER having been stress tested at 55C to their endurance rating in terabytes written (page 39) under a given workload?
        And even then the cherry picked value was in example data submitted by Intel for unknown hardware and very likely extrapolated and quite possibly meaningless because it wasn't part of the chart targeted for the standard.

        The article seems to have totally misrepresented the presentation's purpose: which is to lay out endurance testing methodology/standards.

        The only important values were on page 26 where they set the minimum requirements of 40C 8hr/day load/30C 1 year retention for consumer (with a higher error ratio) and 55C 24hr/day load/40C 3 months retention for enterprise (with a lower error ratio.)
        And it looks like they haven't actually worked out the consumer workload for testing yet.

        • Cherry-picked for "a week" yes, but still disturbing. It's not an issue for datacenters, but for offices.

          Imagine an office PC set next to the radiator - oh, the employees are free to set up their desks as they like, and they really don't care about stuff like that. Given employee going for a holiday break for a month, taking the family for a skiing trip. The PC experiencing 50C on regular basis. That's quite enough to cause the data loss.

          Yes, in a responsible company there will be backups - or the data will

          • by Mashiki ( 184564 )

            I don't know about that. Even at every office that I've ever done work at even the women refuse to sit near/next to the radiators. That includes in super cold areas where it hits -40C to -50C in the late fall/winter. And in the cases where the 'rad' is pumping out 55C temps, there is already 30-100CM of space around them to simply stop possible burns from the rad which gives you plenty of space to normalize the air temperature. Most places are now on forced air from the ceiling.

    • by sribe ( 304414 )

      Yes, it would be insane to use flash memory for archival purposes as well, but it still should easily retain its contents for at least a decade.

      Nope. It's nowhere near that long--more like 1 year, not 10. And that time reduces as the flash wears through being written.

  • There's full shutdown, there's power left on at the wall, there's hibernate with wall power left on, there's sleep. Lots of laptops come with (toshiba, for example) "sleep-and-charge" where they will supply current to USB ports while asleep. I rarely do a full shutdown on laptops or desktops, would this be enough to avoid the problem?

    Or would there need to be a BIOS feature to ensure current supply to SSDs as well as USB ports?

    • Or would there need to be a BIOS feature to ensure current supply to SSDs as well as USB ports?

      there would need to be a hardware feature. the power supply doesn't send power to the drives when the computer is not turned on. they are unpowered even in some sleep modes.

  • no problem (Score:5, Funny)

    by Black Parrot ( 19622 ) on Sunday May 10, 2015 @05:38AM (#49657149)

    Scotty will have the power back just in time.

  • by dshk ( 838175 ) on Sunday May 10, 2015 @05:39AM (#49657151)

    The relevant table is on 27. page.

    In short: if you use the SSD in a cold environment AND store it in hot environment than you may lose data quite quickly. Quicker than two weeks.

    Client drives are also affected, but the data loss occurs slighly later. I guess reason of the difference is that enerprise drives assume a higher work temperature.

    So the advice is that if you use the SSD in your air conditioned basement in a good case then do not store your SSD on the sun for extended periods.

    And no, I do not use spinning media as a backup. I use tapes. Using spinning media for proper backups is almost impossible. See http://www.taobackup.com/ [taobackup.com]

    • by squiggleslash ( 241428 ) on Sunday May 10, 2015 @05:47AM (#49657165) Homepage Journal

      Interesting, because that could affect quite a few businesses in Florida.

      1. Business switches to SSDs. Uses them in a 75 degree air conditioned environment.
      2. Hurricane.
      3. Business unable to get power for a week. Computers down. No power to SSDs. No power for air conditioning. Temperature in office rises to over 100 degrees during the day.

      That's a very likely scenario, especially for smaller businesses (but not small) that wouldn't be organized enough to have back-up power or work from home capabilities.

      • by cfalcon ( 779563 )

        If the step 2 of your failure scenario is "hurricane", you...

        1)- Have plenty of possible mitigation. Hurricans are trackable and reasonably predictable, and you could load your things into an evac van, or back them up, or have a generator. If you don't have a generator, it's super possible to acquire one- those things are sold by the side of the road after a real storm.
        2)- Have a pretty good plan. A hurricane hitting your data center, house, or anything at all is certainly able to destroy it anyway, w

        • I suspect you haven't been through many. Essentially, yes, you get some warnings. 9/10 of those warnings end up going nowhere, with the hurricane making landfall 100 miles North or South, or sweeping by and hitting North Carolina.

          But be that as it may, most smaller businesses know they're going to be crippled anyway in the event of a major hurricane hitting. They expect to offer little but a skeleton service after the hurricane, if that, and many businesses just close for a week until the power comes bac

          • by cfalcon ( 779563 )

            Definitely lost a house in a hurricane and lived in hurricane country for years, so yes, I know what I'm talking about.

            > Essentially, yes, you get some warnings.

            "Some warnings" = Paper talks about it, all over the internet, all over the news, weather station tracks it a huge percent of the time, government issues statements.

            You also have a huge window to evacuate in. This is not some sky-is-falling thing- the power of the storms are well known, their trajectory is iffy when they are mid-Atlantic but w

      • by cfalcon ( 779563 )

        Also, you'd have to get really unlucky to have 100 degree days right after a hurricane. It can happen, but it's by no means likely.

    • The master paused for one minute, then suddenly produced an axe and smashed the novice's disk drive to pieces.

      I'll bet the master is also the one who infected the novice's computer with a virus, and set fire to the novice's building.

    • Using spinning media for proper backups is almost impossible. See http://www.taobackup.com/ [taobackup.com]

      There is nothing in that story to suggest that HDDs are considered inappropriate for backup media. What is your theory? I've used HDDs for deduplicating daily snapshots for the last 15+ years and found them to be every bit as reliable as tapes, and far far easier to use.

    • by dougmc ( 70836 )

      And no, I do not use spinning media as a backup. I use tapes. Using spinning media for proper backups is almost impossible. See http://www.taobackup.com/ [taobackup.com]

      Your link doesn't really seem to explain how using "spinning media for proper backups is almost impossible", so you'll either need to point to exactly where it says that, provide some other reference, or expand on that on your own.

  • by cerberusss ( 660701 ) on Sunday May 10, 2015 @06:41AM (#49657265) Homepage Journal

    FTFS:

    If you have switched to SSD for either personal or business use, do you follow the recommendation here that spinning-disk media be used as backup as well?

    So how do backups help you? Except for ZFS and btrfs (?), no file systems check for data integrity. You're not going to detect the bitrot taking place, and you'll happily send that rotten data to your backup until the corruption is noticed in some other way.

    • by bws111 ( 1216812 ) on Sunday May 10, 2015 @06:49AM (#49657299)

      The bit rot happens when the drives have been powered off for an extended period. The backups are taken before the power is removed.

      • And real backups are taken regularly and retained for a long time. Taking a backup every day and recycling the tape on the 8th day may save money, but won't save your data.

        Backup to disk is not much use (TM).

  • It's too expensive to buy at that volume and not yet proven.
    • To the people saying 'no datacenter goes without power for a week'. I know one that did due to a natural disaster. THey spent 1000's of hours bringing that datacenter up. Do you think they would have wanted to have been messing around reconfiguring raid arrays and rebuilding on top of that? It is not just the data you lose, it is the configuration.
  • I develop on a Lenovo laptop, which ( only ) has an SSD. Anytime I get something done I consider of "historic importance" ( which may simply be simply be a file added to a project, a new method added to a class, an enum having gotten a new value, an interface's signature changed ) I do a commit to version control, with a relevant comment. Version control lives on a server with spinning disks ( RAID-5 ). That server "backs up" to another server - with spinning disks - by rsync, once per hour. THAT server g
  • Bring laptop with SSD to Death Valley, leave it in the car stuck in the sun and go hiking. How long until your data is in trouble? However, I just looked at the specs for the Samsung 840 EVO, since it was the first to pop up:

    Temperature
    Operating: 0C to 70C
    Non-Operating: -55C to 95C

    I would assume the 95C is with data? It would be a rather small caveat if the drive survived but your data was fried.

  • by ITRambo ( 1467509 ) on Sunday May 10, 2015 @08:09AM (#49657489)
    I skimmed though Seagate's paper. At first glance, it appears to have a hidden agenda. That is to make hard drives preferable to solid state drives for everyday use, as Seagate primarily sells hard drives. For long term storage that is what is generally done anyway due to cost, along with tape. For performance, 120+ GB SSD's cannot be beaten, one on one, by any hard drive. Does anyone know of data that indicates that (non-OCZ) drives lose data over time during use, not when powered off for many months after use? Seagate's paper may not be useful if it doesn't correspond to real world use.
  • by Rich0 ( 548339 ) on Sunday May 10, 2015 @08:29AM (#49657579) Homepage

    If you have switched to SSD for either personal or business use, do you follow the recommendation here that spinning-disk media be used as backup as well?

    First, anything stored on any kind of drive should be backed up if you care about it.

    Second, if you do backup, who backs up to SSD? You don't need frequent fast random-access on backups, and SSD is about the most expensive storage technology around per-GB. Anybody doing bulk storage is going to be doing it on either hard disks, tape, or something optical.

    So, if you're backing your data up, you'll be backing it up to something safe most likely.

    Of course, this does bring up the need for the ability to verify the integrity of your data at-rest, and right now I'd say ZFS/btrfs are the best way of accomplishing this. You could also do hashing above the filesystem layer, but that requires a lot of overhead if your files change frequently. If your files don't change much than something like tripwire would be fine. You'd want to run that more often than you rotate your backup media so that you don't discard the last-known-good version of anything.

    • The typical home user that does backups doesnt need much.

      I suggest that the vast majority of backups by home users today are on thumb drives and/or flash cards. Not the greatest method by a long shot, but you can't expect someone with only a couple gigs of photos and music to invest in a real backup solution.
    • No, its a stupid recommendation. Spinning rust doesn't last very long on a shelf. It will rapidly go bad mechanically if you keep switching between shelf and active. SSDs are far superior and data retention is going to remain very high until they really dig into their durability. If you still care, there's no reason why you can't just leave them disconnected from a computer but still powered... they eat no real current compared to a hard drive. SSD-based data retention should be 30+ years if left power

  • Slide 10:

    Unrecoverable Bit Error Ratio = ( number of data errors ) / ( number of bits read )

  • As a data point, at work I took an 80GB Intel SSD from the IT guys' desk drawer (I needed it for a project and that's all he had available as he had a bulk order out). He told me it would probably be blank, since he hadn't used it in over a year. I found a whole PC worth of data on there which I had to format. He was surprised and until reading this article, I really didn't understand why. At least in my case, everything was there and could be read just fine, over a year after it had been written. It w
  • by AcquaCow ( 56720 ) <acquacow@@@hotmail...com> on Sunday May 10, 2015 @11:14AM (#49658379) Homepage

    Newer 3D NAND is using a charge trap design which basically solves the electron leakage issue found with the older floating gate NAND...

    Also, the move to the newer 3D NAND brings us back up to 40nm processes vs the 10nm gates we are currently working with, allowing for much better reliability.

    Disclaimer: I've been selling enterprise flash storage for the last 6 years.

  • These tests explicitly state that the SSD is rewritten until it reaches its endurance rating before the retention test is done. At that point the flash in a consumer would not be expected to retain data unpowered for more than 1 year.

    If you write your data to a fresh SSD once, multiply the number by at least 10.

    -Matt

  • From TFA - consumer SSDs can expect 2 years, which is better than lots of HDs which probably won't spin up. Enterprise SSDs are faster but more ephemeral.

    On the other hand I wouldn't count on this - cell drift is what causes the Samsung 840 slowdown after just a month.

    And yes, I back all my stuff up constantly since I don't want to lose it. To platter drives just because it's much cheaper and speed doesn't matter.

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