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Questions tagged [raid]

RAID, an acronym originally for Redundant Array of Inexpensive Disks (today usually interpreted as referred to as Redundant Array of Independent Disks), is a technology that provides increased storage performance and reliability through redundancy by spreading data across multiple disks using various algorithms (RAID-levels). RAID can be implemented in hardware storage controllers, or in software, usually as operating system/kernel features.

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Do raid controllers syncronize HDD platter rotation?

I'm in the market for a new storage solution. While researching various specs one of my coworkers said that some raid controllers can synchronize HDD rotation to the effect of all drives' sector/block 0 passes under the reading head at the same…
Mxx
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Scaling databases with cheap SSD hard drives

I hope that many of you are working with high traffic database-driven websites, and chances are that your main scalability issues are in the database. I noticed a couple of things lately: Most large databases require a team of DBAs in order to…
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High Failure Rate of Large Drives?

I recently deployed a server with 5x 1TB drives (I won't mention their brand, but it was one of the big two). I was initially warned against getting large capacity drives, as a friend advised me that they have a very low MTBF, and I would be better…
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what is exactly an URE?

I have been looking into RAID5 Vs RAID6 lately and I keep seeing that RAID5 is not secure enough anymore because of the URE ratings and increasing size of the drives. Basically, most of the content I found says that in RAID5, in case you have a disk…
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Can "enterprise" drives be safely replaced by near/midline in some situations?

When specifying servers, like (I would assume) many engineers who aren't experts in storage, I'll generally play it safe (and perhaps be a slave to marketing) by standardising on a minimum of 10k SAS drives (and therefore are "enterprise"-grade with…
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RAID-5: Two disks failed simultaneously?

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…
Mike Furlender
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RAID-6: better to replace two dead drives at the same time, or one at a time?

We have a 16-drive RAID-6 that has three problem drives. Two are already dead, and the third is giving SMART warnings. (Nevermind how it got in such a bad state.) Obviously we want to replace the dead drives before the one that is still working, but…
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Do RAID controllers commonly have SATA drive brand compatibility issues?

We've struggled with the RAID controller in our database server, a Lenovo ThinkServer RD120. It is a rebranded Adaptec that Lenovo / IBM dubs the ServeRAID 8k. We have patched this ServeRAID 8k up to the very latest and greatest: RAID bios…
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Server motherboard died and took Intel RAID controller configuration with it. How do I recover the data?

Old server using a S1200BTS Intel mobo died and has been sitting in a closet for several years. I replaced the motherboard and found that it was originally configured using an onboard hardware raid controller. Harddrives are still in their original…
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Do snapshots + RAID count as a good on-site backup solution?

The two main reasons I can think of for taking backups seems to be taken care of when I use both snapshots and RAID together with btrfs. (By RAID here, I mean RAID1 or 10) Accidental deletion of data: Snapshots covers this case Failure of a drive…
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Can you change the metadata version on an existing array?

So grub requires metadata version 0.90 I'm wondering if I can change my existing arrays to use that instead of the default which is 1.2. That way I don't have to go about a reinstall. If yes, how can I do it?
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Does a RAID controller with an NV cache improve the performance or integrity of an SSD array?

I am planning to purchase a server (Dell PowerEdge R740) with SSDs in RAID 10, and my priorities are write performance and data integrity. It will be running Linux. The SSDs have write caches with power loss protection. It seems like these are my…
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Device: /dev/sda [SAT], 1 Currently unreadable (pending) sectors

I have a software RAID 1 array on RHEL. I am getting this error emailed to me each morning: Device: /dev/sda [SAT], 1 Currently unreadable (pending) sectors When I run a test on sda (or sdb) everything appears to pass. Am I missing…
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Should you still spread a hard drive order over several vendors?

Once upon a time, I was taught to spread an order among at least two retailers whenever I needed around six or more hard drives, and three when the order gets up around 20 drives or more. Use the same make and model of disk, but source them from…
Joel Coel
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Possible to get SSD TRIM (discard) working on ext4 + LVM + software RAID in Linux?

We use RAID1+0 with md on Linux (currently 2.6.37) to create an md device, then use LVM to provide volume management on top of the device, and then use ext4 as our filesystem on the LVM volume groups. With SSDs as the drives, we'd like to see the…
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