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10

The point of RAID with redundancy is that it will keep going as long as it can, but obviously it will detect errors that put it into a degraded mode, such as a failing disk. You can show the current status of an array with mdadm -D: # mdadm -D /dev/md0 <snip> 0 8 5 0 active sync /dev/sda5 1 8 23 ...


10

Does this help? man mkfs.ext3 -m reserved-blocks-percentage Specify the percentage of the filesystem blocks reserved for the super-user. This avoids fragmentation, and allows root-owned daemons, such as syslogd(8), to continue to function correctly after non-privileged processes are prevented from writing to the filesystem. The default ...


8

Open the /etc/mdadm/mdadm.conf file, find the line that begins with ARRAY /dev/md1 and remove the line immediately following which states 'spares=1'. Then restart mdadm service. If you did a mdadm --examine --scan to retrieve the array definitions while the md1 array was still rebuilding, one partition was seen as spare at that moment.


8

From Documentation/md.txt in the Linux kernel documentation: clean - no pending writes, but otherwise active. When written to inactive array, starts without resync If a write request arrives then if metadata is known, mark 'dirty' and switch to 'active'. if not known, block and switch to write-pending If written to an active array ...


8

This is an attempt to summarize from the chat troubleshooting session. The setup turns out to be physical disk -> mdraid raid1 -> LVM. So there are several layers to work through. The old setup was (due to unfortunate prior recovery efforts) not available. However, the NAS gui had been used to create another volume on a different disk, and thankfully the ...


8

It ultimately depends on the implementation of the RAID that's built into your motherboard but often times this "hardware" RAID is little more than software RAID facilitated through some proprietary drivers that will need to be loaded into the OS. If this is the case, IMO, it's almost always better to use the stock software RAID that's included with any ...


7

If you really don't care about reliability, you can use LVM and keep adding physical volumes to a single volume group. That is, you would have a single volume group acting as a virtual drive, made up of several physical volumes (the actual drives). Instead of PC-style partitions, you'd create logical volumes for filesystems and swap. LVM is a good idea ...


7

I found out the answer by asking on the mailing-list. btrfs doesn't do RAID per-volume, but rather on a per-chunk basis. The filesystem reserves "raw" space in (p.e.) 1GB chunks. Initializing the fs with raid1 means that everytime it tries to allocate a chunk, it tries to allocate a copy of this chunk on another device. This architecture allows mixed-size ...


7

Q#1: Can you set up a RAID system using USB sticks as the storage media You should be able to use any block storage devices in a RAID. Any standard directions for setting up a RAID using SATA HDD's should be applicable when using USB storage as well. You'll have to set it up so that the USB devices are assembled as members of the RAID array. Q#2: ...


6

LVM on top of anything is probably a good idea because it gives you quite a bit of flexibility at pretty marginal cost (the extra abstraction layer is really cheap compared to disk I/O). That said, I'd use RAID6, as RAID5 leaves you with no redundancy during a rebuild, which is precisely the time of high stress where drives are most likely to fail.


6

With lvm on top of a raid device you are flexible to create multiple virtual devices (and filesystems) on it. And you are flexible to change the size of those devices. If you are 100% sure that you don't need that and you only need one big filesystem, then you can directly create the filesystem on your raid device. One layer of indirection and complexity is ...


6

You can use lvm for this. It was designed to separate physical drive from logical drive. With lvm, you can : Add a fresh new physical drive to a pool (named Volume Group in LVM terminology) pvcreate /dev/sdb my_vg Extend space of a logical volume lvextend ... And finish with an online resize of your filesystem e2resize /mnt/my/path But beware it's ...


6

I hate to be the bearer of bad news, but... Q: I'm new to mdadm, did I do everything correctly? A: No. In fact, you did just about everything in the most destructive way possible. You used --create to destroy the array metadata, instead of using --assemble which probably would have allowed you to read the data (at least, to the extent the disk is ...


5

Assuming this is linux, this is doable and pretty easy actually. It is covered on the software raid wiki but the basic steps are: Fail and remove drive. Replace with a larger drive. Partition the drive so the partitions are the same size or larger than the ones in the existing software raid partition. Add the partitions to software RAID and wait for it to ...


5

Before doing anything of this sort back up your data to separate media and verify the backup via sha1sum. The process from there would look like Break the RAID1 mirroring so that one of the drives is free Add the third drive to your system Create a degraded RAID5 out of the new drive and the one freed from the RAID1 Copy the data over to the RAID5 volume ...


5

Try this: # cd /var/www # mv html old-html # mkdir -m755 html # mount /dev/md0 html # cp -pr old-html/* html That should mirror the current contents of /var/www/html onto the RAID array. Some notes: The mount command might need tweaking, and ultimately you will want to have an entry in /etc/fstab for it. I assume whatever guide you're using to set up ...


4

This means stuff overflowed and the calculations are meaningless. If you want to get meaningful figures on the read test, you need to make sure the file size is much larger than your RAM, otherwise all you're testing is essentially your RAM speed and the kernel's caching algorithms. Try booting with mem=256M at the end of the kernel boot line, and re-run ...


4

You can force a check of the entire array while it's online. For example, to check the array on /dev/md0, run as root: echo check > /sys/block/md0/md/sync_action I also have a cron job that runs the following command once a month: tar c /dir/of/raid/filesystem > /dev/null It’s not a thorough check of the drive itself, but it does force the ...


4

You may be interested in UnionFS. It may be simpler to setup on an existing system than an LVM. From the UnionFS page, http://www.filesystems.org/project-unionfs.html : This project builds a stackable unification file system, which can appear to merge the contents of several directories (branches), while keeping their physical content separate. Unionfs ...


4

Try running debugfs on the filesystem. Navigate to the parent directory, then use stat to view the inode content and modify_inode to modify it. Note that this may or may not help — if the mode bit has changed, there's a chance that other bytes in the inode are corrupt, including the location of the directory data. Otherwise, fsck may (or may not, recovery ...


4

RAID1 is mirroring, not striping. Furthermore, using BIOS fakeraid is not recommended - Linux software RAID (mdraid) will be more reliable, and will help you to avoid issues like this. If you are absolutely sure you want to installing GRUB on fakeraid, you must follow a quite complicated procedure, that is described here: ...


4

First off, mdraid is configured with persistent superblocks since, well, a long time ago. Configuration is now typically stored internally by mdadm, inside each partition. The only configuration you normally have in /etc is an /etc/mdadm/mdadm.conf, which looks something like this (with a bunch of comments elided): # Please refer to mdadm.conf(5) for ...


4

I found the solution to this issue in the following thread titled: [SOLVED] CentOS 6 on GA-990FXA-UD5. The solution involved removing the BIOS RAID metadata that apparently was part of a residual software RAID that the 40GB HDD must of been used in. Running this command in the CentOS 6.5 LiveCD in a terminal fixed it: $ dmraid -r -E /dev/sda Do you really ...


4

Given that chunks can be quite big and that the parity information is simple XOR (i.e. does not affect data before or after the piece in question) the assumption that only complete chunks can be written does not make sense to me. Chunks are the unit in which data is spread over the volumes. One chunk of continuous data is written to a certain volume, the ...


4

If you're using a standard kernel, it should run on pretty much every hardware, so moving disks from one box to another shouldn't be a problem. That's the theory anyway. However, it may be a different story if it's using some kind of hardware RAID that may not be compatible with another hardware RAID controller. Same for brand-new or exotic hardware that ...


3

Sounds like the device is remote. Assuming linux... ssh remote_host 'dd if=/dev/sdb1' | cp --sparse=always /proc/self/fd/0 new-sparse-file If local... dd if=/dev/sdb1 | cp --sparse=always /proc/self/fd/0 new-sparse-file This gives you an image that is mountable. However, if you pulled it across the network then you had 1.2 TB of network traffic ...


3

LVM and RAID have some similar functionality (both can do mirroring and stripping) but they serve different purposes. RAID is designed to make the storage more reliable, faster and bigger. The differend RAID levels each avchieve one or more of these 3 goals. For example RAID0 gives you speed and more space while RAID1 provides reliablility and fast read. ...


3

If you only need one filesystem in your RAID then there are not real advantages of using LVM. Contrary, without LVM on top you get following advantages: reduced overall complexity better performance Btw, you can resize ext4 filesystems without LVM as well ( resize2fs(8) ). Regarding the performance impact of lvm, some people report decreases by 5 % ...


3

Okay, clearly one of your disks is not active in the array right now. Let's say, under the current enumeration, that /dev/md0 is missing /dev/sdb1. To add /dev/sdb1 back in its former state: mdadm -a --re-add /dev/md0 /dev/sdb1 You may want to re-check the array to make sure the data is all consistent. echo check >>/sys/block/md0/md/sync_action ...


3

Have you looked at ZFS? It sounds like it would do exactly what you are looking for. And because, sometime a video is better than a wikipedia link: check-out this video



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