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6

You may be able to use a tool like ddrescue to image that 3rd failed drive to one of the new drives. This should be an exact copy minus the bad blocks. This way it won't get read errors. Then replace that 3rd failed drive with the newly imaged one. Assuming none of the bad blocks were critical to the RAID or filesystem then you may be able to then assemble ...


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I don't think you can do this from the disk the system is installed to, it should raise an error "device is busy", but you can boot a live disk and change things around. parted http://www.gnu.org/software/parted/manual/html_chapter/parted_2.html for more information on how to use parted.


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From one of the many Google hits on "kicking non-fresh sdb1 from array": This can happen after an unclean shutdown (like a power fail). Usually removing and re-adding the problem device will correct the situation: /sbin/mdadm /dev/md0 --fail /dev/sdb1 --remove /dev/sdb1 /sbin/mdadm /dev/md0 --add /dev/sdb1


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/run/shm can be resized but it won't help as it's a virtual filesystem, a ramdisk. If you want to resize /home you have to check the underlying drives of the /dev/md2 raid (resize, replace or add additional drives to that raid).


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ok im found problem. right command : mdadm /dev/md0 -a /dev/sda1 not : mdadm –manage /dev/md0 –add /dev/sda1 and finally working on ! root@rescue ~ # cat /proc/mdstat Personalities : [raid1] md3 : active raid1 sda5[3] sdb5[2] 1847605568 blocks super 1.0 [2/1] [_U] resync=DELAYED md2 : active raid1 sda3[3] sdb3[2] 1073741632 blocks ...


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I strongly suggest you to try with cache=writeback With recent OS as guests it will be equally safe (if not better) but generally much faster then cache=none. I conducted some tests in the past, you can read more here: http://www.ilsistemista.net/index.php/virtualization/43-kvm-scalability-and-consolidation-ratio-cache-none-vs-cache-writeback.html As a ...


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Unless you are using SSD's already then your two disk RAID1 configuration is going to be extremely limiting for random IO. You need more disk spindles in a configuration such as RAID10 or some SSD's to get more performance. You should also be using VIRTIO as your storage interface on all guests.


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Try to increase md/stripe_cache_size here file which you have to create #/etc/udev/rules.d/83-md-stripe-cache.rules KERNEL=="md*", ACTION=="add", TEST=="md/stripe_cache_size", ATTR{md/stripe_cache_size}="8192" It worked for me on Raid-6 And I suggest you to reduce dirty ratio because it caused me problems on x64 system I use this settings add to ...


1

I know this is a 4 years old post but you can also do this (assuming md0 as the array and sdb4 as the resyncing "disk"): mdadm /dev/md0 --fail /dev/sdb4 && mdadm /dev/md0 --remove /dev/sdb4 This command pretends sdb4 to be a failed disk and therefore kicks it from the array, stopping the resync. If there was no error during the resync-stop ...


2

There is a distinct difference in using disk MD (sda + sdb) or partition MD (sda1 + sdb1), that you seem to lump together. Booting from a whole disk MD is not possible. Therefore, I tend to make partioned MD RAID on the disk/array I boot from. If I have secondary disks that form arrays (like sdc + sdd), I tend to make a whole device MD, make it a LVM ...


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There isn't a set standard (or best practice) that I'm aware of. Different distributions and vendors will have different recommendations for the layout. For an OS installation I'll typically create two MD devices: one for swap (md0) and one for / (md1). If I had to separate OS data from application data I would assign md1 to LVM and create logical ...


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Perform the test again, but change it so you have all five reads being performed on the same MD device (e.g. /dev/md2) and you should see the them being distributed. A single read operation will only read from one drive in a mirror. It will start with the first disk assigned to the mirror, which in this case looks to be /dev/sda. Since you have 5+ MD ...


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It appears all three SSDs are on the same controller and that you're reaching the maximum SATA III speed rating: Third-generation SATA interfaces run with a native transfer rate of 6.0 Gbit/s; taking 8b/10b encoding into account, the maximum uncoded transfer rate is 4.8 Gbit/s (600 MB/s). (source) Your test for writing to all three drives at the same ...



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