Citect SCADA 2018 Disk I/O Devices and redundant servers - Migrating to Persisted Memory I/O Device

Hi Alan ,
Q1\A1: The Disk Device I/O Device address definition defines where these disk files reside. It typically is in the [DATA] directory, so not backed up with a project backup. I don't recommend customers to put runtime data files into project directories, since you can accidentally override them when you restore project backup.
Q2\A2: That procedure looks correct to me. You can test this out on your test bench with two machines to refine this procedure. You could also copy the production Disk Device file to your test environment and confirm all values are migrated correctly. This will same you any headache with the upgrade.
Kind regards
Olivier

You can back up disk tag values using Cicode functions I wrote. Download my Cicode Tools TagTools library from the Citect Toolbox. The TagTools.ci file has TagExport() and TagImport(). They have filtering so you can export tags from a specific I/O Device to a CSV file. For example, if your disk devices all had names ending in _DSK, you'd use the command: 

TagExport("IODEV=*_DSK")

The functions require Citect 7.50 or later, but I've attached a different version that works in 7.20. The export filtering is not as advanced, but it allows you to export from 7.20, then use the 7.50+ version of the function to import the data in the new release.

This Cicode should only be necessary if there's a problem doing the normal upgrade process, such as a corrupt disk device (.CDK) file.

TagTools 7.20.ci

Sorry, I forgot about that. As the toolbox post says, "Most of the functions are stand-alone, but some do call other functions in the same file or other files in this set."

Here are the additional functions my export code calls...from the Date, File, String, and SuperGenie Tools files.

STRING	mcCRLF = "^0x0D^0x0A";	//Carriage Return & Line Feed characters
STRING	msFileBuffer;


//Returns the specified string with nCharsToTrim removed from the left (beginning)
//or "" for out of range values
STRING FUNCTION StrTrimLeft(STRING sText, INT nCharsToTrim)
	INT nTextLen = StrLength(sText);
	
	IF (nCharsToTrim >= 0) AND nCharsToTrim < nTextLen THEN
		RETURN StrMid(sText, nCharsToTrim, StrLength(sText) - nCharsToTrim);
	ELSE
		RETURN "";
	END
END


//Returns TRUE if the specified tag name includes a cluster name prefix
INT FUNCTION TagHasCluster(STRING sTag)
	RETURN StrSearch(1, sTag, ".") > 0;
END


//Wrapper for FileWriteLn() using FileWriteBuf to minimize disk access
FUNCTION FileWriteLnBuf(INT hFile, STRING sText)
	FileWriteBuf(hFile, sText + mcCRLF);
END

//Wrapper for FileWrite() uses buffering to mimimize disk access
FUNCTION FileWriteBuf(INT hFile, STRING sText)
	INT		cMaxChars = 254;	//In Citect 7.20 SP5 and later this can be increased to 255
	INT		nBufferLen;
	INT		nError;
	STRING	sRemainingText;

	nBufferLen = StrLength(msFileBuffer);
	msFileBuffer = StrLeft(msFileBuffer + sText, cMaxChars);					//Copy whatever will fit in buffer
	sRemainingText = StrTrimLeft(sText, StrLength(msFileBuffer) - nBufferLen);		//Remove any text that was copied to buffer

	//Dump full buffer to disk
	IF StrLength(msFileBuffer) = cMaxChars THEN
		IsError();		//Reset error code
		FileWrite(hFile, msFileBuffer);
		nError = IsError();
		
		IF nError <> 0 THEN
			ErrLog("FileWriteBuf() Failed to write buffer to file. Error:" + nError:#);
			RETURN;
		END
		msFileBuffer = sRemainingText;
	END
END


//Wrapper for FileClose() also writes any text remaining in buffer
FUNCTION FileCloseBuf(INT hFile)
	INT		nError;
	
	IsError();	//Clear last error
	FileWrite(hFile, msFileBuffer);
	nError = IsError();
	
	IF nError <> 0 THEN
		ErrLog("FileCloseBuf() Failed to write buffer to file. Error:" + nError:#);
	END

	msFileBuffer = "";
	FileClose(hFile);
END


//Convert a Citect date/time integer value into a formatted string (see Q6123)
//Similar to TimeToStr() but allows custom formats to be specified like TimestampFormat()
//
//sFormat	Custom time/date format specification. Case sensitive. See below.
//nTime		Citect integer time/date value (default is the current time)
//nMS		Milliseconds to add to Citect time (default = 0)
//
//Example: sText = TimeFormat("dd/MM/yyyy hh:mm:ss.fff");
//
STRING FUNCTION TimeFormat(STRING sFormat, INT nTime = TimeCurrent(), INT nMS = 0)
	RETURN TimestampFormat(TimeIntToTimestamp(nTime, nMS, TRUE), sFormat);
END

DiskPLC2.dsk looks like the I/O Device Address, not the Name. What is the Name of your disk I/O device? You have to specify a filter string to match all the disk device names, if they have something in common, like beginning with "Disk_" or ending with "_DSK". Otherwise you need to specify the full name of the device to just export that one device, or leave the filter string blank to export all tags/devices. Another option shown in the documentation for my function is to filter by tagname, like: TagExport("TAG=*\Bkr_Name_*")