> [ ... ] sync=1 really differentiates drives and you really > find which drives are better. [ ... ] It is not necessarily "better" in a strict sense: flash SSD devices with supercapacitor-backed persistent caches can be much faster on 'fsync' heavy workloads, but also cost a lot more (probably mostly because of market segmentation). Of course especially on a RAID5 set with lots of read-modify-write. It is a different performance envelope, not necessarily a "better" one. If one does not need small-write speed then cheaper drivers are more appropriate. However devices which don't have persistent caches and still have high 'sync=1'/'direct=1' speed because they don't implement 'fsync' synchronously are definitely worse, in the sense of having arguably no performance at all. Some manufacturers think that using an SLC cache helps without a persistent-ed RAM cache, but the persistent=-ed RAM seems a lot better to me. -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
