The safest and least test-intrusive way is to calculate the flush time ahead of time and insert the appropriate wait time into the test. I encountered the same issue when testing RAID volumes attached to (shameless plug) HP Smart Array controllers with battery-backed write cache. When the cache (512MB at max config) was filled with random write data it could take a long time for the flush to complete. It was the only way to ensure that the subsequent read-only test data was accurate. -----Original Message----- From: fio-owner@xxxxxxxxxxxxxxx [mailto:fio-owner@xxxxxxxxxxxxxxx] On Behalf Of Dan Le Sent: Thursday, November 18, 2010 3:13 PM To: fio@xxxxxxxxxxxxxxx Subject: How to flush the writing cache before a test with read Greetings, FIO needs to write data files in order to read them. Without disabling the write-cache of the disk, I was wondering if there's a way to flush these data cache to disk right before FIO starts to read these files. I don't want to run every second "sync && echo 3 > /proc/sys/vm/drop_caches" at the same time with FIO because of its incurred overhead. Please help. Thank you, Dan -- To unsubscribe from this list: send the line "unsubscribe fio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html ÿô.nlj·Ÿ®‰†+%ŠË±é¥Šwÿº{.nlj·ŸŠâ^n‡r¡öë¨è&£ûz¹Þúzf£¢·hšˆ§~††Ûÿÿïÿ‘ê_èæ+v‰¨þ)ßø
