| Title: | RAID Software for OpenVMS |
| Notice: | READ IMPORTANT NOTE IN 3.15, V2.4 SSB Kit in 3.17 6 |
| Moderator: | COOKIE::FROEHLIN |
| Created: | Fri Dec 03 1993 |
| Last Modified: | Fri Jun 06 1997 |
| Last Successful Update: | Fri Jun 06 1997 |
| Number of topics: | 341 |
| Total number of notes: | 1378 |
Hello,
We are working on a configuration for a VMS-Cluster with an HSZ40
controller and 38 disk RZ29B. So, we are thinking of putting RAID0-1
or RAID5. Can anyone give us the tecnical advantages and disadvantages
of them. Maybe some document comparing both configurations?
Thank You in advanced,
Marcius/Tula
| T.R | Title | User | Personal Name | Date | Lines |
|---|---|---|---|---|---|
| 327.1 | AMCFAC::RABAHY | dtn 471-5160, outside 1-810-347-5160 | Wed Mar 12 1997 07:09 | 21 | |
That's easy. RAID-5 sucks. RAID 0+1 is much better. You really ought to consider the HSZ50 -- it is much faster than the HSZ40. Also, don't forget to configure dual redundant controllers. I suggest going for the bigger sized cache too. Double up on the power supplies in all shelves. This will limit you to 6 disks per shelf. So, with only 6 SCSI busses coming off the HSZ50, that'll accomodate only 36 disks, not 38. You'll either have to go to another pair of controllers or sacrifice redundant power. How many I/O's per second is required? How many MB's per second? Watch out for the limitations of the KZPSA which is the adaptor used to connect to the HSZ's. Also, you may want to consider RZ28D-VW disks. I'd always prefer two heads seeking in parallel over one. Perhaps a suitable mixture would be best. Have you thought about backup yet? Have you thought about quorum yet? What about disaster tolerance? | |||||
| 327.2 | COOKIE::FROEHLIN | Let's RAID the Internet! | Wed Mar 12 1997 11:21 | 16 | |
It all depends. RAID 0+1 has higher redundancy and higher availability.
It has much better I/O performance than RAID 5. RAID 5 on the other
provides a minimum kind of redundancy (one failure) and comes at a
lower cost (one extra disk per array instead of duplicating each drive
in an array). Especially with larger arrays an extra controller is
needed to connect all the drives for RAID 0+1.
RAID 5 has poor WRITE performance. Application with average write
percentages below 20% are possible candidates for RAID 5 arrays.
RAID 5 arrays are very well suited for archived data or retrieval only
applications.
If extra disk/controller costs are a lesser issue and overall high
I/O performance is needed then RAID 0+1 is the right solution.
Guenther
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