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20

RAID-5 is a fault-tolerance solution, not a data-integrity solution. Remember that RAID stands for Redundant Array of Inexpensive Disks. Disks are the atomic unit of redundancy -- RAID doesn't really care about data. You buy solutions that employ filesystems like WAFL or ZFS to address data redundancy and integrity. The RAID controller (hardware or ...


18

What you have is evidently not hardware RAID but software RAID with a BIOS interface, often called fakeRAID. The main job of putting the disks in an array is done by the Windows driver. Related reading: How do I differentiate “fake RAID” from real RAID? There are two advantages to hardware RAID over software RAID: it's independent of the operating system ...


12

You should not mount it directly using mount. You need first to run mdadm to assemble the raid array. A command like this should do it: $ mdadm --assemble --run /dev/md0 /dev/sdc1 If it refuses to run the array because it will be degraded, then you can use --force option. This is assuming you don't have /dev/md0 device. Otherwise, you need to change this ...


8

Don't panic, this is a common and recoverable error. Your hosting company set up a two-disk redundant array to protect the data in case one of the disks fails. This failure has now occurred. The output indicates that sda1 has failed, and that the RAID1 array is working, but degraded. Right now you're on borrowed time, though. If the second disk fails, that ...


8

Whoever told you that RAID 10 is somehow inherently slower than RAID 1 doesn't know what they're talking about. That makes the rest of the question unanswerable as it's based on a false assumption. Further reading: What are the different widely used RAID levels and when should I consider them?


8

You don't need to do anything other than replace the failed drive. There's no need to move the FSMO roles, even if DC1 is offline for a short period of time. If for some reason DC1 can't be brought back online after the drive replacement then you can seize the FSMO roles. Here's some additional info: http://www.petri.co.il/seizing_fsmo_roles.htm


8

You can fail the /dev/sdb device through mdadm (best make sure you fail the entire device i.e. all mds that runs off it) then check it for errors, but from what you are describing you are most likely better off just replacing the device. I have had ide devices that failed on a regular basis, I kept re-adding the rejected device until finally the computer ...


8

Sort of. It is a valid test of failure (the ability of your system to keep running), but not a valid test of your controller's repair mechanism (it's ability to assimilate a replacement drive) unless you also format or otherwise wipe the disk before re-inserting it. I would test this for a scratch volume before placing it into production, and document ...


8

Try: zpool detach BearCow da1 See if it spits out any error messages or resolves the issue. This should automatically happen when the resilvering is done, but it looks like yours hung for some reason. There's additional measures that can be taken if this doesn't work. It should work, but it also shouldn't be necessary in the first place.


7

You may have misunderstood someone. RAID-5 is slower than RAID-10 on writes, but RAID-1 can be treated as a RAID-10 with a single pair of disks, and thus has the same performance per "spindle" as RAID-10. The best recommendation for SSD on a database is to use RAID-5. The rebuild time on the incredibly small and fast SSD drives is very good. Since you'll ...


6

This depends entirely on the type of RAID (software or hardware) and the storage controller that is implementing RAID. I'm the vast majority of implementations, there is no service interruption to the host system (that's the whole point of RAID). There is usually some kind of notification about the failure of a hard drive that an administrator must be made ...


6

I asked a NetApp engineer who was giving us a talk this very question. His answer, more or less, was: Nobody reads the checksums on reads. There's no point. Reading a checksum means you have to read the entire slice plus checksum, then compute the checksum to verify you have the correct data. Plus the orthoganal checksum if you are running ...


6

I believe that the answer depends on the controller/software for example it is quite common for mirroring systems to only read one disc out of a pair and therefore be capable of delivering the wrong data. I note that if your results depend on that data the when the data is written to both discs it is then corrupted on both discs..... From the pdf under ...


6

Since you created 2 logical disks, that's what you get in Disk Management. The P400 presents logical disks to Windows, not physical disks. The health you see in Disk Management is the health of the logical volumes. That will not reflect, for example, a failure of one of the physical drives. You will need to monitor that using HP Array Configuration Utility ...


5

From my point this is a very bad idea, RAID 1 was never designed to be a backup solution, but a redundancy tool. That said there are tons of tools that allow you to backup a complete drive ( snapshot) which will work rather fast as well, for instance drive image XML on windows. Linux certainly has the same or similar tools available.


5

Drive "resync" occurs if a drive swap happens and the RAID is being rebuilt by the system. In RAID 1, this means copying the entire drive. You can use the OS as normal, but it's will noticeably slow and during sync you do not have redundancy as the RAID is in a degraded state.


5

Yes, this is possible. See: Can I convert a 1 disk RAID 0 to RAID 1? You're lucky that your striped array has worked until now. The process you'll go through is an "array transformation". Make sure your system has a battery-backed cache (BBWC) on the RAID controller. Add two more disks of equal or greater size than the existing disks. Install the HP ...


5

You can force a check of (eg) md0 with echo "check" > /sys/block/md0/md/sync_action You can check the state of the test with cat /sys/block/md0/md/sync_action while it returns check the check is running, once it returns idle you can do a cat /sys/block/$dev/md/mismatch_cnt to see if the mismatch count is zero or not. Many distros automate this ...


5

I have not yet tried the new LVM segment types, but the overview is that they are support for the Linux MD RAID personalities in LVM. That is, they are RAID levels 1, 5, 6 etc. using the MD code with the eventual goal of removing the duplicate functionality of LVM's mirroring and having both MD and LVM use the same code. This is very new stuff so may not be ...


5

This would be a poor idea overall. Vendor implementations of RAID vary, of course, so you will get different behavior with different vendors. Most assume that drives are significantly identical, so aren't designed to handle disks of such different performance characteristics. Chances are very good your performance will be handicapped by the slower disk. For ...


5

To replace a failed motherboard with a new motherboard and to then reconfigure Windows to work with the new motherboard, do the following: Turn off the computer. Replace the existing motherboard with the new motherboard. Insert your Windows Server 2003 CD in the CD-ROM drive or the DVD-ROM drive, and start the computer from the CD. When you are ...


4

It sounds like you are using Linux Software RAID, and you've got the RAID devices set up using partitions instead of whole disks. In this case simply failing the partition won't help you: The failing drive (hardware component) is what's throwing the errors. Any time the operating system tries to access that hardware component you'll have problems, and ...


4

You can add a newer, larger, disk directly to the machine and use Disk Management from the System control panel to add mirrors of the existing partitions to the new disk. There will be a performance hit as the disks sync, and then a slight tax in normal operation, but having tolerance for a disk failure is easily worth it, as long as this doesn't need to be ...


4

The use-case here is flawed. The one use-case where this makes sense is where your I/O activity is majority-read by a very large degree (like 9:1). In that case, since there are so few writes the HD can keep up with the changes coming from the SSD. If the ratio is any less then that, then the SSD risks outpacing the HD's entire write ability. What you're ...


4

man mdadm: -W, --write-mostly subsequent devices listed in a --build, --create, or --add command will be flagged as 'write-mostly'. This is valid for RAID1 only and means that the 'md' driver will avoid reading from these devices if at all possible. This can be useful if mirroring over a slow link.


4

Backup the server and test the backup Update the server - BIOs, PERC firmware, disk firmware - everything (contact Dell support for help with that) Go into OMSA (install OMSA if you don't have it - Dell support can provide a link) In OMSA go to the Logical Disk, from the drop down menu choose "reconfigure" and if you have enough drives, it will let you ...


4

A self-speaking excerpt from man mdadm: -W, --write-mostly subsequent devices listed in a --build, --create, or --add command will be flagged as 'write-mostly'. This is valid for RAID1 only and means that the 'md' driver will avoid reading from these devices if at all possible. This can be useful if mirroring over a ...


4

You may also want to check for the existence of a cron job which regularly runs a RAID check on the mirrors. This can look a lot like a resync while it's happening. On CentOS-type systems, it's done by /etc/cron.weekly/99-raid-check; I don't know what that'd be on a Debian system, though. Edit: That's a weekly cron job that runs a RAID check, which causes ...


4

Unless the controller and the drives support hot-swap unplugging one while the system is running is very risky. They'll probably survive but you could potentially permanently upset the controller on the drive or, worse, the machine's I/O controller. So unless everything supports hot-swap, unplug the drive while the machine is not running then start it up ...


4

What all do you have on the machine? If it were me, I'd just promote one of my secondaries, and rebuild from scratch. I'm always trying to find time to upgrade mine though, so, you know, grain of salt. Or you could cheat, and make a VM image out of the PDC, and run it off another piece of hardware while you fix the old hardware. I like doing this with a lot ...



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