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Yes, that implementation satisfied the FUA criteria. I am not going to comment on how good of an implementation decision that method is, but it should not be considered out of spec. Nathan -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Pat LaVarre Sent: Thursday, June 26, 2003 3:55 PM To: [EMAIL PROTECTED] Subject: [t13] fua write means what This message is from the T13 list server. > Subject: RE: [t13] hmmm.. no comments? Once upon a time I saw a fua write implementation that received the write data into cache, flushed the whole cache, and then copied status in. This meets "the added restriction that the data must be to the medium before the drive can say the transaction is complete. That's it." But then the worst case time to complete the write rises with size of cache. Is that ok? That implementation doesn't fit well with the sometimes popular concept of a time limit applied per command without regard to cache history or blocks per command. Pat LaVarre -----Original Message----- From: Nathan Obr [mailto:[EMAIL PROTECTED] Sent: Thu 6/26/2003 3:44 PM To: T13 List Server Cc: Subject: RE: [t13] hmmm.. no comments? This message is from the T13 list server. I am sending this as a test. I haven't been able to get onto the T13 List Server yet although I have been trying to reply to this thread for a while. I apologize if I reawaken the issue. For those who were not at the T13 meeting this week, the original issue has been resolved and hopefully the below clarification will resolve any outstanding ones. ------------------------ [My original, long delayed email] Everyone has made far too big of a deal out of this. First off, FUA doesn't affect queuing or write ordering. The only difference between FUA I/O and other types of I/O is that FUA has the added restriction that the data must be to the medium before the drive can say the transaction is complete. That's it. The drive may still queue the command and handle it however it sees fit. It seems like there should be more to it, but there isn't. Hopefully, you can see that there is no need for concern over overlapped LBA or affects on the queue as it doesn't affect write ordering or the queue. By the way, before too many people decide to jump ship for T10, you will be interested to know that SCSI has had support for FUA for quite some time (See SBC). Many hard drive manufacturers shouldn't have a problem implementing this as much of it can be borrowed from their existing SCSI lines. Nathan
