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Editor to share with you what Oracle11g RAC+ASM pre-installation storage planning considerations are, I believe most people do not know much about it, so share this article for your reference, I hope you can learn a lot after reading this article, let's go to know it!

Storage planning is not about adopting the most technologically advanced, but about adopting the most appropriate business needs. Let's start with the general principles:

1. According to the principle of separating the storage locations of data files, backup files and archive log files, it is best to put them in different disk groups rather than different Lun of the same disk group, but the disadvantage of this method is that each disk group needs a hot spare together, which leads to a serious waste of space.

2. If it is an OLTP system with frequent reads and writes, it is best to use Raid1+0 for the disk groups where data files and archive log files are stored, so as to ensure that both reads and writes are fast. Online log files (online redo logfile) and control files are placed in both the data area and the archive area at the same time, which can improve availability and recoverability while ensuring read-write performance. The disk groups stored in backup files can be redundant in the way of Raid5.

3. The general way is to store data files, backup files and archive log files in two different disk groups, rather than different Lun of the same disk group, and to Raid1+0 both disk groups. This will not affect performance, and can save a hot spare to improve space utilization, but if the amount of data is large, it is estimated that backup disk space will be wasted through the partition of Raid1+0.

According to the above contradictions, we can see that an important factor is the size and number of disks, and it is necessary to take database size and specific applications into consideration.

At the same time, it is not recommended to use too large hard drives in other areas except the backup area. If the database is small and the number of disks is too small, you might as well make all the disks into Raid1+0, which can improve the overall bandwidth of Icano and save space waste caused by multiple hot spares.

With the sharp decline in the price of SDD disk, it is also appropriate to use the mixed use of SDD and SAS, because the IOPS of a SAS disk with a rotational speed of 10K is only 120 to 150, while the IOPS of a SSD hard disk is even more than 10 times, so it is worth trying this combination for systems with high performance and concurrency requirements. For example, suppose an OLTP system with a customer database with a current size of 1T, data increment of 100G per month and concurrency of more than 1000. You can take the following two types:

After 6 900GB hard drives are finished with RAID5 group and hot spare, the actual available capacity is 4: 900GB / 3.6TB, 7 SSD disks are mainly online data. After RAID5, the actual available capacity is 5*400GB=2TB.

Configure 11 SAS disks with 15k rotational speed, do RAID1+0, partition two Lun, and further divide them in ASM

For databases with large space capacity, in addition to the above factors, another important factor is the number of ASM disk groups (ASM DISKGROUP) and the (ASM DISK) size of each ASM disk required by the disk group. ASM disk group is not easy to have too many, the name should be standardized as far as possible, for example, it can be divided into DATADG1,DATADG2. , DATADGn to store data files and log files, FRADG1,FRADG2... , FRADGn to store archives (including backup files), BACKUPDG1,BACKUPDG2... , BACKUPDGn to store backups, etc. For ASM disks under each ASM disk group, combined with database size and future growth, it is best to use the appropriate size, which is not easy to be too small or too large. For example, if the incremental size of the database is 3T in 3 years, it is best to control each ASMDISK size in the range of 200G to 500G. Why, because if calculated at 300G, then 3000G/300G=30 ASMDISK, so that when forming disk groups in ASM, it also looks neat and reasonable. If there are too many disks, it will not only lead to confusion and human error, but also bring some administrative overhead to manage so many disks for ASM.

Finally, some DBA may adopt the disk management mode of placing archives and backups in a separate LUN and using the file system instead of ASM, which has the advantage that even if the ASM fails to log in, the backup and archive files can be directly seen on the file system, avoiding certain risks and reassuring. If you use this mode and use the LINUX operating system, it is recommended that the file system be divided according to the LVM mode of Linux, so that it is very convenient to expand in the future. However, this method also has some disadvantages, that is, because it uses the local file system of Linux rather than the Cluster file system, the archiving and backup of the two nodes are implemented in such a way that the two nodes write independently only to their own partition and can share read-only. If you accidentally configure the partition of each other into a mount mode that both sides can read and write, it will lead to the problem of data overwriting and loss.

The above is all the contents of the article "what are the considerations for storage planning before Oracle11g RAC+ASM installation". Thank you for reading! I believe we all have a certain understanding, hope to share the content to help you, if you want to learn more knowledge, welcome to follow the industry information channel!

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