Re: Disk Layout

Steve Romankiw wrote: :> :> I have been unable to find information reguarding the pros & cons of :> RAID and ODS. :> :> We are running Sun Solaris 2.5.1 with VxVM and ODS 7.23 UC1. We :> planning for some expansive growth in our database(s). In our Sparc :> :> Some of the questions I have are: :> :> Q: Should I simply create two partitions per drive? This creates two :> 2gb partitions which the max chunk size for ODS. :> :> Q: Should I employ RAID 0+1? Get the benefits of striping and :> mirroring? :> :> Q: Is your decision different based upon OLTP vs DSS? Yes, the decisions are most definately based on weather or not your system is OLTP or DSS. In OLTP situations you typically do quite a bit of updating, so something like RAID5 with its write performance hits can be a problem. With DSS on the other had, you are primarily reading, so the RAID5 is not a problem. The informix system we are setting up sounds similiar to your environment. A Sun Ultra E3000 (2x167MHz) with 256MB RAM running Sol2.5.1 and Informix 7.23. We have a MTI 3200 Gladiator disk array with active-active RAID controllers interfaced through two Performance Technologies PT-SBS450D Ultra/Wide host adapters. We've configured 60GB as RAID5 for dataspace (lun 0), 26GB as RAID5 for index space (lun 1) and 26GB as RAID0 for temp space (lun2). Some preliminary benchmarks on the RAID using a program called 'iozone' gave us the following: (all numbers are in MB/sec) WRITES: lun0 lun1 lun2 -------------------------------- 0 only 4.9 1 only 4.5 2 only 6.25 0+1 4.7 4.4 1+2 2.7 2.7 0+1+2 4.3 2.6 2.6 READS: lun0 lun1 lun2 -------------------------------- 0 only 7.3 1 only 8.3 2 only 8.3 0+1 6.8 7.8 1+2 4.3 4.3 0+1+2 7.0 4.1 3.9 Lun 0 goes thru one PT-SBS450D while Lun1 and lun2 share the second PT-SBS450D. The iozone program generated a 400 MB file which it used for writing and reading. We chose a file this large to insure two things: 1) that we were larger than the RAID's cache and 2) that we were larger than the system's memory. The reads and writes were much larger when we used smaller files, due to the caching effects of the RAID and the system memory. Since our system will be used as a DSS, the slow write rates do not concern us too much. - Al -- Al Dorrington awdorrin@ictest.delcoelect.com Delco Electronics - IC CIM Database & Unix Administrator Kokomo, Indiana, USA Phone: 765.451.9655