Layout disks

Your logical logs help with fast recovery, but also allow you to recover in the event of catastrophic disk failue (which of course will NEVER happen with EMC!!). So, you use the ontape daemon to back each one up as it fills, usually to tape but sometimes to an independent disk device. In this case you really want many small logs rather than one big one, because with large logs many minutes, or hours, could pass before enough activity occurs to fill one and have it backed up, leaving you exposed in the event of the need of a full restore. Christian Kondo wrote in message <86q3r4$gvh$1@news.xmission.com>... > >Hi everybody, > >I'll have to configurate the layout disks in my system. We are upgrading our >machines, and we'll use SHARK storage server. (its works the same way EMC). >My database size is about 400 Gb with SAP, I'll have to use an IDS 7.30.FC10 >or the last release in S80 server (AIX 4.3.3). >My main doubt is how I create the logical disks ? One big disk or many >littles ? I say again, logical disks, so the most important thing is the >block size that it will have (I guess ...) > >Thanks in advance ! > >Christian Kondo >System support specialist - SAP/Informix >IBM Global Services - Technology Center Brazil > >______________________________________________________ >Get Your Private, Free Email at http://www.hotmail.com >

Hi everybody, I'll have to configurate the layout disks in my system. We are upgrading our machines, and we'll use SHARK storage server. (its works the same way EMC). My database size is about 400 Gb with SAP, I'll have to use an IDS 7.30.FC10 or the last release in S80 server (AIX 4.3.3). My main doubt is how I create the logical disks ? One big disk or many littles ? I say again, logical disks, so the most important thing is the block size that it will have (I guess ...) Thanks in advance ! Christian Kondo System support specialist - SAP/Informix IBM Global Services - Technology Center Brazil ______________________________________________________ Get Your Private, Free Email at http://www.hotmail.com

Christian Kondo wrote: > Hi everybody, > > I´ll have to configurate the layout disks in my system. We are upgrading our > machines, and we´ll use SHARK storage server. (its works the same way EMC). > My database size is about 400 Gb with SAP, I´ll have to use an IDS 7.30.FC10 > or the last release in S80 server (AIX 4.3.3). > My main doubt is how I create the logical disks ? One big disk or many > littles ? I say again, logical disks, so the most important thing is the > block size that it will have (I guess ...) OK, I will suggest that you subdivide the storage into at least three independent arrays of separate drives. One each for any filesystems (if you will have filesystems on other drives ignore this part); one small array for rootdbs, and logical and physical logs; and the third, and largest array, for your data disks. I recommend RAID10 for rootdbs/logs and data using 2 or three small drive pairs for rootdbs/logs and as many drive pairs as needed to create an array of over 400GB. At this size you may want to make three data arrays say 10 pairs of mirrored 16GB drives each for a total of 480GB (or 9 pairs each for 432GB). For the filesystems, I honestly don't care, let the sysadmin do what he/she likes. For the Informix arrays make the stripe sizes small, 16 to 32K (rather than the 64 to 128K preferred for filesystems) if your software/firmware and drive manufacturers support it try to vary the stripe size with the drives' sector zoning so that a single block read never spans a cylinder gap, this can mean big performance gains. For Informix you have no choice, you have to partition the arrays into many 2GB (or smaller) logical drives as Informix can only use 2GB per chunk and cannot have an offset beyond 2GB either. (Someone posted a message recently indicating that Informix on AIX can use 4GB partitions, I don't know myself.) Art S. Kagel