(I've been lurking the mailinglist archive for a few months already, I think bcache sounds really interresting) Hello Joseph, > Carrying out some scalability tests on high I/O systems. More tests to > come using the Phoronix Test Suite. > > Fio summary: > 24 jobs > Direct IO > Randwrite test > Total of about 80k IOPs at 3.5k IOPS per thread. > > Test rig specs: > 2x Intel(R) Xeon(R) CPU X5650 @ 2.67GHz (12 physical cores, 24 logical) > 12x 2TB Seagate nearline-SAS in RAID6 on LSI Logic / Symbios Logic LSI > MegaSAS 9260 > 2x Intel 520 SSDs 120GB in RAID0 > > The 2 520s are striped with md raid as /dev/md0 whch is formatted as a > bcache cache device using 1M buckets and 8k hard block size > Backing device is the big old raid6. > > Random IO performance of the native raid0 is about 96K IOPs, backing > device in the realm of 1600ish. > However the backing device has a sequential IO performance of about 1.5GB/s. > So why do you put your SSDs in RAID0 ? If you are using RAID6 for your HDD you obviously care about your data, shouldn't you be using RAID1 or let bcache do some RAID1-like behaviour* ? Because when you use RAID0 your data will only be written to one SSD. * I think bcache had some ability to handle that sort of automatically. > Below are some quick findings using fio - showing very good > scalability of bcache even with very very fast SSDs. > *Note: The SSDs are connected via a SATA2 interface being somewhat of > a bottleneck. Have a nice day, Leen. -- To unsubscribe from this list: send the line "unsubscribe linux-bcache" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
