Re: Best Oracle configuration for HP DL585, six 6402 controllers and 42 disks?

Narrowing down the disk configuration options. Assuming that we will spread all disk usage over all the disk and over all HP 6402 controllers (S.A.M.E) so no separate disks for redos etc.

Setup 1: Each controller driving 7 disks will be configured RAID 1+0 with hot spare. Oracle ASM is used to tie together the six logical raw devices (one logical raw device per controller). ASM is set to use no redundancy, just striping the data over the six raw devices. Capacity: 6*6*146 GB = 5256 GB. Failure tolerance: disk failures are toleared well since there is mirroring and hot spare in every logical raw device and the controller will start using the spare if a drive fails. Controller failures are not tolerated since ASM stripes over the six controllers and if any controller goes down, all data goes down.

Setup 2: Each controller driving 7 disks will be configured RAID 0 without hot spare. Oracle ASM is used to form two failgroups each of which consists of three logical raw devices (one logical raw device per controller). ASM does striping and mirroring so that each block is written on both controller sets. Capacity: 6*7*146 GB = 6132 GB. Failure tolerance: one disk failure on one RAID 0 set will be tolerated since all blocks are written to two RAID 0 sets. There could be also multiple disk failures on one RAID 0 set or a couple of disk failures on different RAID 0 sets as long as one ASM failgroup gets no failures. Controller failures are tolerated: any one controller could fail without data loss and also two or three controllers could fail if they are in same ASM failgroup.

Setup 3: Each controller driving 7 disks will be configured RAID 1+0 with hot spare. Oracle ASM is used to form two failgroups each of which consists of three logical raw devices (one logical raw device per controller). ASM does striping and mirroring so that each block is written on both controller sets. Capacity: 0.5*6*6*146 GB = 2628 GB. Failure tolerance: disk failures are toleared well since there are mirroring and hot spare in every logical raw device and the controller will start using the spare if a drive fails. Controller failures are tolerated: any one controller could fail without data loss and also two or three controllers could fail if they are in same ASM failgroup.

Setup 4: this would be all 6402 controllers set to JBOD mode and ASM configured to stripe and mirror over the disks and controllers (two failgroups, each of which having 21 disks on 3 controllers). This could be the optimal solution but since 6402 has no JBOD mode we can forget about it.

Comparison: Setup 1 tolerates disk failures but no controller failures. Setup 2 has rather a limited disk failure toleration but it tolerates controller failures. Setup 3 tolerates both disk failures and controller failures but the disk capacity is cut to half.

Performance comparison: Setup 2 is assumed to be the fastest since seven disk RAID 0 sets are used. Setup 3 is the slowest at least in write operations since every write goes to two controllers and four disks. Received on Wed Apr 26 2006 - 14:42:52 CDT