DL380 and RAID

[scott_417]

I have some questions in regarding to the configuratio of DL380:

1) How many arrays can I have and should I have? (Can I put all six disks in one array?)
What is the advantage to use single array vs multiple arrays?

2) What is the meaning of RAID 5 drive set "with online spare"?

3) If I want to realize:
Disks 1 and 2 for OS (raid 1)
Disks 3 and 4 for log files (raid 1)
Disks 5 and 6 for data files (raid 1)

Will the RAID disk controller automaticall "know" how to do it? (or I have to intervene?)

4) Between RAID 1 and RAID 5, which is generally better, or more popularly used?


Thanks to help

Scott

[Steven Clementi · Accepted solution]

Scott:

1. With 6 internal disks, you can have a maximum of 6 Arrays, 1 for each disk. not the way to go.

You can put all 6 disks in 1 array. The advantage would be better performace since you have more spindles in the array.

2. Assume you have 6 disks in an array. 1 of them is a Hot Spare. You now have 5 disks of usable space. With a RAID5 logical drive, max available/usable space is now 4 disks.

3. You can do that. You have to tell it what to do. During the Smart Start setup or using the Online RAID Configuration utility built into the firmware of the Smart Array, you tell the controller what configuration you want.

4. RAID1 (technically RAID 1+0) is said to have the fastest fault tolerance load, and is good for write-intensive applications.

RAID1 is generally used for OS, Log Files, Cluster Quorum's, etc whereas RAID5 is generally used for Database Data, dependong on the type of database.

RAID 1 and RAID 5 can each survive 1 disk failure.


Steven

[Plamen Radev]

Scott,

Assuming you have 6 disks in your enclosure, I woul arrange these as follows:
(a) Array_1 - HDD1 & HDD2 (RAID1) for the OS & DBMS; usable space equals 1xHDD capacity;
(b) Array_2 - HDD3-HDD5 (RAID5) for the data; usable space equals 2xHDD capacity;
(c) assign HDD6 as on-line spare to both Array_1 and Array_2; in case of any single HDD failure of either Array_1 or Array_2 the controller will assign the on-line spare to that array and rebuild the data to that disk.

In any case you should use ACU to build the arrays and assign the on-line spare.