1Answer iSCSI write cache 17.7k Views 12 Rosa Pinto A PHP Error was encountered Severity: Notice Message: Undefined index: userid Filename: views/question.php Line Number: 191 Backtrace: File: /home/prodcxja/public_html/questions/application/views/question.php Line: 191 Function: _error_handler File: /home/prodcxja/public_html/questions/application/controllers/Questions.php Line: 433 Function: view File: /home/prodcxja/public_html/questions/index.php Line: 315 Function: require_once Asked: Aug 17,2020 In: Performance 1 Answer Rosa Pinto Punditsdkoslkdosdkoskdo Asked: Aug 17,2020 In: Performance iSCSI write cache Is there a way to setup on a Linux iSCSI initiator a local disk partition for write cache ? The data would be first written on some high performance local disk and then in a second time on capacitive disks mounted through iSCSI. Thanks performance iscsi Your reply on this question: Add Reply Cancel 1 Véronique Lakhal Aug 17,2020 so are you asking for a 3 tiers vs the normal 2 tiers (not counting the local hd cache) of caching as in the system os will cache disk io then you want something like a layer of ssd then a final write to spinning disks? Or should you just buy more ram so the os can cache more disk io? 1 Rosa Pinto Aug 17,2020 The use case is to write a lot of data faster than the 1Gb ethernet link is able to transfer to the disks enclosure. The hardware cache is on the enclosure side (so after the ethernet bottleneck). So the idea is indeed emulating an SSD layer. 2 Bibiana Fiuza Aug 17,2020 Beware, a writeback cache does NOT mean more throughput in many situations. It must be flushed regularly. This flush has to happen over the ethernet link, so you will still be limited to your link speed during sequential write. If you are making many small changes sporadically, a writeback cache will perform beautifully. However, it will be nearly useless in a sequential write pattern or heavy continuous random writes, such as a backup, media, or highly active database server. The same is true of a read cache in most situations.