In the interests of performance and recoverability, InterSystems recommends a minimum of four separate file systems for InterSystems IRIS, to host the following:
Installation files, executables, and system databases (including, by default, the write image journal, or WIJ, file)
Database files (and optionally the WIJ)
Primary journal directory
Alternate journal directory
On UNIX®, Linux, and macOS platforms, /usr/local/etc/irissys
is the InterSystems IRIS registry directory and therefore must be on a local filesystem.
In the event of a catastrophic disk failure that damages database files, the journal files are a key element in recovering from backup. Therefore, you should place the primary and alternate journal directories on storage devices that are separate from the devices used by database files and the WIJ. (Journals should be separated from the WIJ because damage to the WIJ could compromise database integrity.) Since the alternate journal device allows journaling to continue after an error on the primary journal device, the primary and alternate journal directories should also be on devices separate from each other. For practical reasons, these different devices may be different logical units (LUNs) on the same storage array; the general rule is the more separation the better, with separate sets of physical drives highly recommended. See Journaling Best Practices
in the “Journaling” chapter of the InterSystems IRIS Data Integrity Guide
for more information about separate journal storage.
Current storage arrays, especially SSD/Flash-based arrays, do not always allow for the type of segregation recommended in the preceding. When using such a technology, consult and follow the storage vendor’s recommendations for performance and resiliency.
In addition, this section includes information about the following:
Content Date/Time: 2019-01-15 00:45:58