Hi, > -----Original Message----- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] > Sent: Mittwoch, 10. April 2002 21:47 > To: Vorsprach, Bernd; [EMAIL PROTECTED] > Subject: Solaris raw partition devspaces? > > > > Ok, I do have a few questions. I put down this: > > param_adddevspace 1 DATA dev/rdsk/c0t9d0s3/$SID/DATA0001 R 62500 > > but it should actually be this: > > param_adddevspace 1 DATA dev/rdsk/c0t9d0s3 R 62500 > > Now to explain the parts: > > 1 --> Is the number of devspaces that will be put on this partition or > slice.
wrong: Its the index of the devspace to add. Each devspace must get its own unique index. > > DATA --> Is the type of devspace. > correct > dev/rdsk/c0t9d0s3 --> Is the raw slice/partition that I'm using. > > R --> Is the type of partition, in my case I'm using raw > partitions for > just data and log, but not sys is that right? correct > > 62500 --> Is the size of each devspace that is being created. correct, unfortunatly it is the size in 8K pages of the devspace. To get it you must take the physical size of the devspace in KByes divide it by 8 and substract 1 for a header page that is always needed... > > Now, my questions are. Should I just use one raw partition > pre disk, I say > yes, Is that right? That is fine. > Should I use multiple devspaces on that raw partition, > so for example if I had a 2GB partition, should I create one > devspace of 2GB for that partition or should I create four 500MB > devspaces on that raw partition to make for better access time? Use only a single devspace on a single raw partition (see below). > Does that even matter for raw devspaces? It is actually not even possible to create several raw devspaces on a single raw partition, since there is no devspaces offset into a raw partition, which would be needed... > As you can tell, I've never really used raw partitions, and I > hate to do anything that I don't fully understand. I have a > db running now on raw partitions, but I want to make sure I understand > completely before creating a production db to start using. The reason, why it is not meaningfull to setup several devspaces (file or raw) on a physical disk, is that all I/O is unbuffered! That means we are not using a system I/O buffering but write through directly to the disk. The only effect of several devspaces on a disk are more I/O writer threads and less control about seek operations. Raw devspaces pass the file system overhead and the file system buffering. The number of I/O writer threads can be controlled (Parameter _IO_PROCS_PER_DEV). Furthermore if you have more than one devspaces on a single disk, some background tasks will try to equalize usage of the devspaces, by doing copy actions between the partitions. Such is good, if separate physical disks are used, to allow more I/O operations to be executed in parallel. I hope you can see now, there are good reasons, to put several physical disks into a system, but not to split the disk space into several devspaces. CU jrg > > > Thank You, > > Justin A. Stanczak > Web Manager > Shake Learning Resource Center > Vincennes University > (812)888-5813 > > > > > > "Vorsprach, Bernd" > > > <[EMAIL PROTECTED]> To: > [EMAIL PROTECTED] > > Sent by: cc: > > > sapdb.general-admin@lists > Subject: RE: Creating a DB? Disregard, I've got most of it > figured out. > erv.sap.com > > > > > > > > > 04/10/02 01:26 AM > > > > > > > > > > > > > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] > > > I took a break and started in again. I believe I have it > figured out. > > I just have simple questions: > > The way I understand it, I only need one devspace per disk if I'm > > using raw devspace. Is this correct? > > Yes there is no reason to split a disk in more than one devspace. > > [...] > > param_adddevspace 1 DATA dev/rdsk/c0t9d0s3/$SID/DATA0001 R 62500 > > param_adddevspace 1 DATA dev/rdsk/c0t11d0s1/$SID/DATA0002 R 62500 > [...] > > You have to increase the devspace number in the command > param_addddevspace: > > param_adddevspace 1 DATA dev/rdsk/c0t9d0s3/$SID/DATA0001 R 62500 > param_adddevspace 2 DATA dev/rdsk/c0t11d0s1/$SID/DATA0002 R 62500 > param_adddevspace 3 DATA ... > > param_adddevspace 1 LOG dev/rdsk/c0t9d0s1/$SID/LOG001 R 31250 > param_adddevspace 2 LOG dev/rdsk/c0t11d0s0/$SID/LOG002 R 31250 > > > Bernd > -- > SAP Labs Berlin > _______________________________________________ > sapdb.general mailing list > [EMAIL PROTECTED] > http://listserv.sap.com/mailman/listinfo/sapdb.general > > > > > _______________________________________________ > sapdb.general mailing list > [EMAIL PROTECTED] > http://listserv.sap.com/mailman/listinfo/sapdb.general > _______________________________________________ sapdb.general mailing list [EMAIL PROTECTED] http://listserv.sap.com/mailman/listinfo/sapdb.general
