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Multiple Disks

By shreeram44 ·
Hi,

We are configurerinf an application setup where in we need very large file system. We have four controllers and in each set there are 18 GB X 5 disks. We are using VXVM software for disk partitioning. We used to create many small size partitions for this purpose. WHat Happens if we create one big volume? In this case if one controller fails what happens? Is there any performance improvement? Can you post the procedure how to do this please.

Thanks,

Sreeram.

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Multiple Disks

by ustutz In reply to Multiple Disks

The specific procedures depend on the OS you are using. You have to consider three aspects of multidisk environements:

Disk Spanning: Allows you to create file systems that are too large for just one disk. If one disk fails, your file system fails.

Disk Striping: Improves performance by splitting data in small chunks over several disk - accessing the data in parrallel. If one disk fails, your file system fails.

Disk Mirroring: Duplexing / duplicating data on two (or more) disks.If one disk fails, the other one takes over.

In any of these schemas you want separate your data across different disks as well as different SCSI controllers and power supplies. If one SCSI controller fails, all disk on that controller fail. Ifthat controller contains both disks of a duplexed/mirror pair, the whole filesystem just failed.

Note that striping, spanning, and mirroring are not mutually exclusive. Just complex to plan out. Best solution - if resources (money) permit, would be hardware RAI

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Multiple Disks

by shreeram44 In reply to Multiple Disks

The question was auto-closed by TechRepublic

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Multiple Disks

by MShavrov In reply to Multiple Disks

How I understand, if you have posted this question into the UNIX forum, you have to install UNIX OS. First thing is hardware solution. How it was explained in the first answer, you can do various RAID variants, MIRRORING (if it's required) and join all drives into one GAINT partition.
Another point is software configuration. If your application will require very big hard drive resources, you should ttry to make one big partition by hardware. But you should keep in mind that it's better to haveseparate partitions for OS sensitive directories. For example, you should create root partition, /usr, /var, swap partition etc. in separate filesystems to keep it independent from 'disk overfill'. And rest of space you can assign (and mount) to directory, where application will use it.
It's 'simplest' solution.

Get luck.

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Multiple Disks

by shreeram44 In reply to Multiple Disks

The question was auto-closed by TechRepublic

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Multiple Disks

by MShavrov In reply to Multiple Disks

How I understand, if you have posted this question into the UNIX forum, you have to install UNIX OS. First thing is hardware solution. How it was explained in the first answer, you can do various RAID variants, MIRRORING (if it's required) and join all drives into one GAINT partition.
Another point is software configuration. If your application will require very big hard drive resources, you should ttry to make one big partition by hardware. But you should keep in mind that it's better to haveseparate partitions for OS sensitive directories. For example, you should create root partition, /usr, /var, swap partition etc. in separate filesystems to keep it independent from 'disk overfull'. And rest of space you can assign (and mount) to directory, where application will use it.
It's 'simplest' solution.

Get luck.

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Multiple Disks

by shreeram44 In reply to Multiple Disks

The question was auto-closed by TechRepublic

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Multiple Disks

by Aaron V In reply to Multiple Disks

There is much to consider here.
Is this a business critical application?
Does this need redundancy? How much data is there going to be? How fast will it grow? What type of data is it?

Once you have determined those answers, then address the hardware requirements.

If I need vast storage, high speed, and data redundancy, I would go with an EMC Symmetrix (I know they are expensive) or a Hitachi(also expensive) system. For speed, use Fibre connections. For more speed, use an alternate/aggregate pathing package. Both vendors support these packages.

The problem with one huge logical disk, as I understand it, is that SCSI is going to wait on a write ack, and will not send another write until it gets the ack. So, you may havea bottleneck if you are going to do mostly writing.

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Multiple Disks

by shreeram44 In reply to Multiple Disks

The question was auto-closed by TechRepublic

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Multiple Disks

by mbitto In reply to Multiple Disks

Veritas will allow you to construct the one large volume, howver, this will expose you to other risks, such as no redundancy or mirroring, and that in the unlikely scenario that the log files get large enough, this would cause large problems. Backups may take longer, depending on the type of backup software being used. Is this system mission critical? Do you need the OS partitions to be mirrored?

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Multiple Disks

by shreeram44 In reply to Multiple Disks

The question was auto-closed by TechRepublic

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