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OpusretisFlag for Switzerland

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Migrate from RAID 1 to RAID 5 HP DL380 G6 with smart array P410i controller

I want to migrate our RAID 1 to RAID 5.
1. We've got a smart array P410i Controller. In the manual under migrating a logical drive is explained that this will need a battery buffered write cache.
How can I check if I have one in this server?
2. Does anyone have experience with migrating the RAID Level with this controller? Is it possible to do it online with the HP System Management Tool in graphic mode?
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Bawer
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if you are migrating then you have to simply break the raid other wise its not possible, insert the server repository CD and start the fresh installation.
You are aware that the performance will change. If the the drive has Exchange or SQL logs or Exchange 2007 databases you may find performance issues... (could be other things as well)
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You ought to read that a bit closer, it's talking about disks with a BER or 1 in 10^14, these ones quite likely have a BER of 1 in 10^16. Whilst RAID 5 isn't good performance these disks aren't cheap.
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I use only SAS drives.
I thought that the amount of spindles will bring a better performance.
What's now the truth?
As there is no duplication its worse. You need to read the data from every disk appart from the parity disk for a read, and write to every disk for a write.
You might want to read this:

http://en.wikipedia.org/wiki/Standard_RAID_levels

then you can decide which is best for your application. RAID-5 optimises available storage, not performance, Thats why the battery backed up cache is important. That allows the RAID card to tell the OS the write is complete, when it really isn't. The data is just in the cache and is written to disk "later"
I see.

Can I put a second RAID 1 into the Controller without risk and interruption?
you may not...
my standard setup for a server was two 73gb raid1 for os and 4 320gb for data in raid 10 - virtualization and iSCSI SAN has changed this quite a bit - iSCSI SAN is all raid 10 - disc i/o rocks!
Of course you can put two more disks in and create a second RAID 1 array, or you can add two more disks to the current array and expand it to a wider RAID 10 array. Again, same as RAID level migration, array expansion requires a cache battery (but creating a second array doesn't need one).

What disks do you currently have?  That'll tell us whether they are enterprise horizontally encoded ones that have a very low error rate or hte higher capacity vertically encoded ones that have higher error rate. Bear in mind that the 500GB SAS ones are near enough SATA ones with SAS interface boards on.
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Thanks PowerToTheUsers.
Is the performance realy a problem with RAID5.
We've got 10 Users who working on this terminal server. The server is virtual.
Will migration to RAID 5 realy come to perceptible less performance?
As g4ugm stated, it's most likely to become a problem in SQL and Exchange environments, which have rather high I/O-demands. Running a Terminal Server probably won't give you performanceproblems.
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The cache (256MB probably) will go a way to offset the RAID 5 write penalty assuming they get a battery for it. Whilst RAID 10 is better you're talking $400 for a single 300GB SFF disk.
Raid 5 does not optimize performance but it can perform well. As stated before, the number of spindles are the key. There is a certain amount of overhead in breaking down a write request and putting a small piece on each disk. With enough spindles, you overcome the time lost for that processing due to the larger number of smaller writes. This break point is frequently about 5 disks in a raid 5. Having said that, the raid 5 will still not perform as fast as a raid 10 but is much more economical than a raid 10 for the same amount of space. You just have to compare your needs vs the cost. Not everyone needs the performance of a raid 10 just because it's better.

Made up example:
4 x 100GB drives
Raid 10
200GB of space with optimized performance

Raid 5
300GB of space for the same cost with less performance

2 x raid 1
200GB of space, no special performance increase

Do you need the space or the performance more?