FCI is said to be an HA solution. If one node crashes, it spins up the 2nd node so why is it said to not be a DR solution? There was a disaster at node 1 and node 2 picked up from there. Isn't that isaster recovery? Further lets assume that the disk is replicated, then can we say that it is a DR solution? Here if node or disk crashes, we have the other node or disk to take over. Isn't this disaster recovery?
122489
Throughout MS documentation for AlwaysOn Availability Groups (AG) and AlwaysOn Failover Cluster Instances (FCI) I see the following pattern:  FCI is for HA scenarios. An AG synchronous secondary replica, co-located with the primary, is for HA scenarios. An AG asynchronous secondary replica, in a different datacenter, is for DR scenarios.  Here is an . Since option #1 and #2 are both for HA scenarios, how do I decide between them? If MS published costs and RPO/RTO metrics for both #1 and #2, it would be fairly easy to decide which I want. Or perhaps there is a different way to understand the ROI differences between these options.  For example, perhaps option #2 is best suited for VLDB's and option #1 is best suited for very high transaction volumes.  I don't know. So again, what is the selection criteria a DBA uses to choose between options #1 and #2? To further complicate things, I know that options #1 and #2 can be combined!  When is it wise to combine the two options?  When is it pointless to combine the two options?  I know when these options are combined, the AG no longer supports automatic fail-over.  It's interesting trivia, but doesn't answer my question. Incidentally, I intend on provisioning my final solution into Azure IaaS.  If I use an Always On FCI, I will likely create the quasi-SAN using Storage Spaces Direct (S2D). Update I've found two articles that give a comparison.  The first is , and the other is .  Both have a chart like this: ╔═════════════════════════════╦══════════════════════════╗ ║ FCI                         ║ AG                       ║ ╠═════════════════════════════╬══════════════════════════╣ ║  * Server Level             ║  * Database Level        ║ ╠═════════════════════════════╬══════════════════════════╣ ║  * Requires shared storage  ║  * Uses direct           ║ ║     (SAN or Storage Spaces  ║     attached storage     ║ ║     Direct)                 ║                          ║ ╠═════════════════════════════╬══════════════════════════╣ ║  * RTO from 30              ║  * RTO typically less    ║ ║     seconds to 20 minutes.  ║     than 30 seconds      ║ ╠═════════════════════════════╬══════════════════════════╣ ║  * RPO: no data loss.       ║  * RPO: ???              ║ ╠═════════════════════════════╬══════════════════════════╣ ║  * Only Passive Secondaries ║  * Active or Passive     ║ ║                             ║     Secondaries          ║ ╠═════════════════════════════╬══════════════════════════╣ ║  * One SQL Server           ║  * Multiple SQL Server   ║ ║     instance/license        ║     instances / licenses ║ ╚═════════════════════════════╩══════════════════════════╝  The article didn't comment on AG RPO, but I read elsewhere that there is no data loss when recovering from a synchronous secondary replica.  I don't know if that is true and I don't know what the RPO of asynchronous secondary replica might be.  In Azure there is  are created with the AG (regardless if you have your own domain controllers).  I don't know if an Azure FCI has the same heavy-handed requirement. Most significantly - I still don't know why it is valuable to combine the two techniques.  I've only read that it  availability.  That is a vague claim IMO. More trivia: I also spotted a discussion suggesting that .
102125
I have an HP Proliant DL360 G6 server with 8 HD bays.  Currently I have the first two bays working with ESXi and I'm just running RAID 0 on a single drive.  This is not a production machine.  It has a P410i Controller.  I'm trying to add a third drive to machine and when I go into the controller menu at boot time and select "Create Logical Drive" it says I've reached the max of 2 logical drives.  I was under the impression I could many more logical drives than just 2?  I'm not a server admin by any means, so this is definitely not my strength, but any help would be greatly appreciated.  Thank you.
14500
A recent issue with a Buffalo TeraStation NAS here in my office has got me investigating Raid 5.  I've found a few different articles talking about the unsuitability of using raid 5 in large arrays, or with large disks  Here is one  that talks about problems with rebuilding an array with large consumer drives.  I'm trying to work out what counts as 'large'?  The NAS we have here is a 4 drive Raid 5 setup, each drive is 1 TB. A drive failed and has been replaced, the array is currently rebuilding.  Does this setup constitute as large, in terms of will likely have a problem during the rebuild?  How reliable is this setup for day to day use?
974
I am on a MacBook Pro 13 running latest Sierra. I have an external Seagate solid state hard drive that was working and out of the blue stopped working. The only thing on it was my Adobe Lightroom images/videos. Not the LR DB files. I'm sure you have all heard this woe before, so I won't dwell on that. And yes, I back up to the cloud. AWS S3 specifically. Though I am traveling South East Asia for the last year, and staying in cheap hostels. So good internet is hard to come by sometimes. I can't back it up after every export. While most of it is backed up, there is some that is not.  Moving on. The symptoms seems to change every time I plug it in. The first sign was it ejected on it's own. I plugged it in again, and it wouldn't mount. Disk Utility recognized it, so did the command line diskutil list but it wouldn't mount. I rebooted and it worked for a second. Then I could only get to it from the command line. Then trying to frantically back up to my local what was not backed up to the cloud, it all failed. Basically just a cp -R [directory] [local-directory] command.  After some more frantic unplugging and re-plugging plus some command line manual mounts, I finally got it to where the Disk Utility would be able to run first aid on it. It failed. I don't recall the error. So I put it in a freezer. After a few hours I tried again. It is not any better. It still will not mount. Now Disk Utility sees it, but with no partition. I can't even give me information about how much space is used on it.  I have also tried it from a Windows machine. It did not mount. I have tried other cables. No success. As well as tried my other USB port. I also have another working external hard drive exactly like the one giving me issues. It works on all cables and USB ports.  I do have Docker running with a Ubuntu container, I'm trying to think of a way to see if I can try to get to the USB from there. I also have a USB that I have thought about running a live Ubuntu on there to see if I can mount and retrieve the data or fix the HDD that way. But if it will not mount, I doubt these will work.  Can anyone else think of any other tricks I can try myself to see if I can repair this or at least retrieve the data without paying for a service or software? If not, those suggestions are also welcome.  Update   I made the mistake in original post that it was a Solid State Drive. This is my mistake, it is actually a spinning disk hard drive. I bought them long ago and have been traveling with them for so long I just forgot. Question is updated to reflect this. Now diskutil list does not show it at all. The Disk Utility app also does not see it. Based on suggestion from @Allen I seeked out the USB to SATA cable. I did not quite find it, as my options are extremely limited where I am at. Though a local expat on a facebook group was able to help me with a empty 2.5 casing that I was able to extract the drive from original casing and put it in his blank case. It now mounts. Though it has the "click of death" sound to it. And data is not really reachable. While I can ls the directories and Adobe Lightroom does not have the exclamation mark when it can not reach the actual external files. Right clicking on the images and clicking on "Show in Finder" or any other variation of trying to get to the files through Finder or terminal, I have no success. It usually hangs and I get the spinning wheel. Since Adobe Lightroom imports these images into directories named by date, I am going to send the drive off to a data recovery service and ask to recover just unbacked up directories i.e. dates. Next time I will make harder efforts to backup and probably get an actual SSD.   I think this can be closed, due to my low reputation points I can not close this myself.
40165
When I plug in a removable 1TB USB disk in my laptop, the operations led keeps blinking for a while and then you can hear the servo mechanism resetting with a short "tack".  I'd like to recover the data.    I believe there might be some way to get the data through low level IOs.    What I believe is that the mounting process assumes the disk is OK and I should prevent this before using ddrescue or something similar.  Does anybody have a solution to this problem?
59594
I'm planing an age replacement policy for our storage and servers. Most of them are for DBs and some for images (static content) so yes, they have an huge I/O everytime.  Also, we use Samsung 840 Pro SSDs for the RAID Controllers (PERC H700i) as CacheCade.  Are you guys managing the replacement of old hard drives and solid state drives?
20221
Saw this in the reopen queue tonight    The question is closed as off-topic/general-computing and the OP apologizes for having to post it here.   Sure enough, that is what the company directs customers to do:  From:       Need some help? Ask a question on Stackoverflow with the tag    nitrousio and our developers (and other developers) will reach out to help you.      newest questions tagged nitrousio - Stack Overflow      ....list....   I guess no one anticipated that not all product support questions will be valid programming questions.  Or maybe it is about turning support into a profit center by attracting other customers.  Not sure that makes sense, though.  I mean, I'd like private support tickets when I contact a service provider.   This has been addressed previously back in 2009 by Jeff Atwood in an answer to   However, there is a newer 2012 duplicate  where the answer is effectively "OK, if..."  I thought I would post this here so the community can chime in on where the limits of this kind of thing should be and enable the proper people to take care of it.
108744
We have a Dell PowerEdge T410 server running CentOS, with a RAID-5 array containing 5 Seagate Barracuda 3 TB SATA disks.  Yesterday the system crashed (I don't know how exactly and I don't have any logs).  Upon booting up into the RAID controller BIOS, I saw that out of the 5 disks, disk 1 was labeled as "missing," and disk 3 was labeled as "degraded." I forced disk 3 back up, and replaced disk 1 with a new hard drive (of the same size). The BIOS detected this and began rebuilding disk 1 - however it got stuck at %1. The spinning progress indicator did not budge all night; totally frozen.   What are my options here? Is there any way to attempt rebuilding, besides using some professional data recovery service? How could two hard drives fail simultaneously like that? Seems overly coincidental. Is it possible that disk 1 failed, and as a result disk 3 "went out of sync?" If so, is there any utility I can use to get it back "in sync?"
19324
I have a Dell PowerEdge R415 and R515 and wondering how I can be alerted remotely when a hard drive fails in either server? Both are running RAID, so I need to be notified, so I can swap out the drive. Both servers only have the basic Baseboard Management Controller. Is this possible with a third party tool/software?
66275
I have added this entry to my /etc/fstab   /dev/sdb1 /user_data xfs rw 0 0   Which works fine, the issue i am getting it sometime i remove this drive and when i do and  reboot my machine it goes into emergency mode.  I have tried adding   /etc/systemd/system/local-fs.target.d/nofail.conf    with  OnFailure=  in it but i  still get the same result  is there something else i can do to stop this happening   Thanks
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While a similar question was raised , it doesn't seem to be a solid answer but more of a theory. In addition my case is a bit different as you will see below.    You will note that I have two home drives, one being a mount to a share on my NAS and the other in question being the one within localhost.  What value do the home and net drives within localhost serve other than being part of default *nix folder structure? Is this anything more than a local representation that exists by *nix default? Is it safe to eject these drives or is the OS using them in some fashion which may not be readily apparent?
110103
The battery back-up (BBU) model:   admin enables write-back cache with BBU writes are cached to the RAID controller's RAM (major performance benefit) the battery saves uncommitted and cached data in the event of a power loss (reliability)   If I lose power and come back within a day or so, my data should be both complete and uncorrupted.  The downside to this is that, if the battery is dead or low, OR EVEN IF IT IS IN A RELEARN CYCLE (drain/charge loops to ensure the battery's health), the controller reverts to write-through mode and performance will suffer.  What's more, the relearn cycles are usually automated on a schedule which may or may not happen in the middle of big traffic.  So, that has to be manually disabled and manually scheduled for off-hours if it's a concern.  Annoying either way.  NV caches have capacitors with a sufficient charge to commit any uncommitted-to-disk data to flash.  Not only is that more survivable in longer loss situations, but you don't have to concern yourself with battery death, wear-out, or relearning.  All of that sounds great to me.  What doesn't sound great to me is the prospect of that flash module having an issue, though.  What if it's completely hosed?  What if it's only partially hosed?  A bit corrupted at the edges?  Relearn cycles can tell when something like a simple battery is failing, but is there a similar process to verify that the flash is functional?  I'm just far more trusting of a battery, warts and all.  I know the card's RAM can fail, the card itself can fail - that's common territory, though.  In case you didn't guess, yeah, I've experienced a shocking-to-me amount of flash/SSD/etc. failure :)
92544
I have opened Disks program today and noticed that there is FAILING in the Assessment column for the SMART status.     What does this error mean? Is it serious problem?  I have Lenovo G50-45 laptop, disk is SEAGATE ST1000LM014-SSHD-8GB(LVD3) 1TB SSHD with 8GB NAND Flash (original disk in this latop).  Update 2017-09-24:  The disk has died yesterday. 1 year and 3 months have passed since 1st hint of problem. About 4 months ago I had few issues with it not booting, but I was able to make another clean install. Since yesterday the disk is non-responsive. As this was long expected I had backup of all important data.(!) The disk was about 2 years old, so that was quite premature death.
60646
We're planning to install a SQL Server on this physical architecture:  A hyper-v cluster based on windows server 2019 A cluster shared volume where all VMs live A full-flash SAN that contains the CSV  I've always read that is a common best practice to have multiple disks for data files, log files, temp db files ect... But that best practice is referred to a bare-bone installation. So, what I'm asking is: what are the actual benefits of doing so on the above described architecture (if any)?
11471
I'm trying to detect what filesystems a kernel can support. Ideally in a little list of their names but I'll take anything you've got.  Note that I don't mean , just ones that the current kernel could, theoretically support directly (obviously, fuse could support infinite numbers more).
113271
Can HDD platters theoretically be interchanged that one could recover data from a HDD in which something else might be damaged? I am interested if it is technically possible, whichever effort is needed for that. This might also be of interest for forensic research.
121897
I'm looking for Windows 7 software that will allow me to quickly create a "checkpoint", do whatever I might need to do to my computer - install programs/drivers/updates, create/delete personal files, reboot the system multiple times, open questionable attachments - and then revert the entire system back to when the checkpoint was created.  Essentially I want Windows Restore Points that save my personal files and partitions, too.  It sounds like disk imaging might be the ticket, but creating them is much too slow and the restore process too involved... I'm hoping to sacrifice full disaster recovery for speed. Creating a checkpoint should be as close to one-click as possible, and rolling back should be a matter of selecting a restore point and rebooting. Ding!  I'm familiar with Sandboxie, True Image Home "Try and Decide", Returnil, and a number of other "virtual system" apps that actively "catch" changes and allow you to commit or reject them. I'm not interested in these for a number of reasons - I prefer the "cut and dry" restore point approach.  Finally, I'll note that I've just recently become aware of . It sounds absolutely perfect, however, a quick skim through the user forums show more than a few horror stories of corrupted, unbootable systems. Any positive personal experience with the software to suppress my superstitions, or suggestions for more established alternatives would be greatly appreciated - Comodo Time Machine seems relatively new. I'm willing to purchase unbloated, quality software.  Thanks for your help!