The Chicken Littles The concern over the failure rates of drives have always been an issue. After all, Shannon's Noisy channel theorem explains that we can get arbitrarily good error-correction simply by increasing the block lengths a bit, and sacrificing a tiny amount of overhead. I know ZFS people report checksum errors but how much of that is just regular bad sectors? ng_rebuild"Unrecoverable read errors (URE) present as sector read failures, also known as latent sector errors (LSE). navigate here
However, I do still see some with WD Black, and with some Intel SSDs. permalinkembedsaveparentgive gold[–]FunnySheep[S] 0 points1 point2 points 1 year ago*(6 children)I would rather base decisions on studies than personal anekdote, that's the reason for this topic. Your array has failed. Offices in London, San Francisco and Sydney.
https://github.com/zfsonlinux/zfs/commit/bb3250d07ec818587333d7c26116314b3dc8a684 From what I understand Illumos and BSD have this same issue until they pull in this patch that was only committed on June 22, 2015. When blocks of flash or sectors of a disk are permanently unreadable (one type of URE) then the sector is marked bad and a "spare" sector is mapped in. And why ZFS copy-on-write is really a much better writing mechanism for 4kn drives than some alternatives.). Where's the advantage to the vendor?
Oracle contributes code to many open-source and free software projects. My previous 18 TB MDADM array never had an issue, but those 1 TB Samsungs were rated as 1015. Bad blocks, sectors , areas on the harddrive, that the drive itself and the OS is not aware of. Ure Raid 5 So RAID 5 for consumer hard drives is dead.
The error rates for some drives are appallingly high, for others strikingly low. Demand better SATA drives for your RAID. Pick the correct RAID level (RAID 10 or RAID 6) and enterprise class hard drives when required. The assumption is that the RAID controller will be able to recreate the unreadable sector in memory using the data found on the other drives in the RAID array - it
I'm conservative here because that 25 TB is an average over time (I'm now at 30). Zfs Ure If you have a 2TB drive, you write 2TB to it, and then you fully read that, just over 6 times, then you will run into one read error, theoretically speaking. With 6TB drives I am beyond the math. Please let that sink in.The problem is that once a drive fails, during the rebuild, if any of the surviving drives experience an unrecoverable read error (URE), the entire array will
Yes, budgets are tight, but don't risk your data. Every article about URE's starting with this one: http://www.zdnet.com/article/why-raid-5-stops-working-in-2009/ Scares you with the 12.5 TB number. What Is Unrecoverable Read Error I very frequently see pools with a disk that has 1-10 checksum errors. Unrecoverable Read Error Nero Apple's thrown you a lifebelt SpaceX to explosion conspiracy theorists: there's no grassy knoll at Cape Canaveral 130 serious Firefox holes plugged this year Spotlight Windows Server 2016 persistent memory support
In most cases, is a block or two here or there. check over here permalinkembedsaveparentgive gold[–]mercenary_sysadmin 0 points1 point2 points 1 year ago(1 child)Also, there's something you should really think about here: the lies told by vendors on their spec sheets Why would vendors lie on their Calendar October 2008 M T W T F S S « Sep Nov » 12345 6789101112 13141516171819 20212223242526 2728293031 Blogroll iCanHasCheezBurger Kev’s Blog The Daily WTF XKCD - the That means that there is a chance that you get a read error every 12.5 TB of data. Ure Definition
Thank you very much! Sure, you can move to better enterprise drives if you want to minimize the chances of loosing a file or block of files effected by the loss of that sector, but Maybe the XS models have it ?Either way, in a Raid setup you'll want disks to fail in a predictive way - and when they fail you'd want them to fail http://crimsonskysoftware.com/unrecoverable-read/unrecoverable-read-error.html Literally, it seems as though you relied on the video to make your point.
RAID5 must only be applied with some wisdom only for small arrays or VDEVs. Ure Rate Increasing drive capacities and large RAID 5 instances have led to an increasing inability to successfully rebuild a RAID set after a drive failure and occurrence of an unrecoverable sector on These types of errors are seemingly referred to with 3 different names: Bit Error Rate (BER) Unrecoverable Bit Error (UBE) Unrecoverable Read Error (URE) However, these all refer to the same
I'm glad for the opportunity! d_handling"Modern drives make extensive use of error correction codes (ECCs), particularly Reed–Solomon error correction. We have a market need and someone, somewhere will come along and fill that need with a new way to provide robust redundancy. Raid 6 Forum rules This is a user forum for Synology users to share experience/help out each other: if you need direct assistance from the Synology technical support team, please use the following
The numbers go up by an order of magnitude (ahem, multiply the number by 10) for each 10^x improvement you make. RAID 6's dual parity mechanism provides additional cushion in the event of drive failures (at the cost of performance), while RAID 10 setups can lose up to half the disks before According to you, we are simply doomed by your calculation in reading any disks you are going to get a read error eventually and sooner than you really would hope for. weblink There is 12TB worth of data to be read from the remaining three drives before the array can be rebuilt.
The head may not be able to lock onto the right place, the data may have been overwritten by a later error or any dozen of other possible failures. The checksumming is not how ZFS saves you BTW, it's the fact that ZFS does file-level RAID and not block level RAID right? Disclaimer: I am an Oracle employee; my opinions do not necessarily reflect those of Oracle or its affiliates. In larger environments with hundreds of drives you mostly wont notice.I'm not very strong in linux, but I know DSM is linux based, using "mdadm" built in capabilities with a bit
The NAS vendor and HDD vendor talk to each other and share trade secrets in order to achieve reliabilty and predictability.While Synology support many drive types and vendors, i do 't I see considerably fewer now than I did years ago - largely because I use pricier drives now.