Nitman
Copper

Replacing hard drives

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Dear all,

I'm new to working with servers, raid's and hard drives that can be hot swappable. In our organisation we have two servers. Both in Raid 5 and on Poweredge 2950. One server was one month ago showing a failed hard drive, the other one is showing a removed hard drive, both in the open manage server administrator.

On the server that showed failed hard drive I took it out and put it back in to see if it would rebuild. It did but the size of the raid is not back to extended so it must have failed and now I will replace it. However I would like to ask you if I need to do any step in the server before I physically replace it?

On the other server. Which step do I follow so it sees the hard drive and adds it to the raid?

One final question. In the virtual disk info I saw that I can do a consistency check on the drives. If I start that, will that interfere with working with these servers (meaning should I do it after work hours)? Can there be any problems doing that? If regularly, how often should I do that?

Thanks for help about these!

Nitman

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Moderator
Moderator

RE: Replacing hard drives

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Hello

On the server that showed failed hard drive I took it out and put it back in to see if it would rebuild. It did but the size of the raid is not back to extended so it must have failed and now I will replace it. However I would like to ask you if I need to do any step in the server before I physically replace it?

I'm not following you here, what do you mean by "the size of the raid is not back to extended"? The size of the array should not change if a drive fails. The virtual disk size is a constant regardless of drive status. If a drive fails that would cause the virtual disk size to be smaller then the disk does not contain redundant data and the array will go into a failed state.

If you plan to replace a drive that is being used in an array then you should offline the drive before removing it to reduce the risk of data corruption.

On the other server. Which step do I follow so it sees the hard drive and adds it to the raid?

If you insert a blank drive into the system then it should automatically start rebuilding into the array. If it does not automatically rebuild into the array then set it as a hot spare.

One final question. In the virtual disk info I saw that I can do a consistency check on the drives. If I start that, will that interfere with working with these servers (meaning should I do it after work hours)? Can there be any problems doing that? If regularly, how often should I do that?

Yes, you should expect a 30% decrease in performance during a rebuild or consistency check. Some of our firmware will allow you to adjust the percentage used for these tasks, but most of our controllers have it locked at 30% maximum to avoid the system becoming unusable.

A good rule of thumb for a consistency check is once per month. A consistency check is a preemptive measure. Running a consistency check while there is no redundant data is pointless. A consistency check will use redundant data to correct any issues with the array data.

Thanks

Daniel Mysinger
Dell EMC, Enterprise Engineer

Get support on Twitter @DellCaresPRO

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Nitman
Copper

RE: Replacing hard drives

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Ok, I see my lack knowledge about virtual disks and arrays. From your answer to my first question I gather that the array size doesn't change if one drive fails. It just goes into failed state and waits for the failed drive to be replaced. There is also the issue that I don't fully understand how the previous IT man set these servers up. Is it safe to write ask that on this forum and write the details of our servers? I'm not sure where to turn for understanding this.

Thanks,

Nitman

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Moderator
Moderator

RE: Replacing hard drives

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I don't fully understand how the previous IT man set these servers up. Is it safe to write ask that on this forum and write the details of our servers?

Yes, you should avoid including any personally identifiable information. Do not include your WAN IP address, email addresses, service tags, company name, or any other information that could be used to commit fraud, DDOS, or any other malicious activity against you.

Thanks

Daniel Mysinger
Dell EMC, Enterprise Engineer

Get support on Twitter @DellCaresPRO

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Arvind Naik
Copper

RE: Replacing hard drives

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I'm working with servers, raid's and hard drives that can hot swappable. In our organization we have Dell Power edge 1950 servers. Both 250GB * 2 in Raid 5 and on server. Now client ask for upgrade with 3 TB of 2 HDD. Please help me in this.

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whoever80
Copper

RE: Replacing hard drives

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Hi Daniel,

I'm actually having the same problem. Our server is configured as Raid 10. There was a hard disk fail. We replaced a new hard disk but there is no option for us to add the new disk to the raid group. The only option is to assign the new disk as hot spare.

Is there any way to include the new disk back to the existing raid group?

Thanks.

Tee

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theflash1932
Diamond

RE: Replacing hard drives

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Is there any way to include the new disk back to the existing raid group?

Yes. Add it as a hot-spare.

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