My wife is in the market for large, cheap drives with decent performance to store sequencing data, so I ordered and tested a 2 TB Western Digital Red NAS (WD20EFRX—no link because wdc.com is broken at the moment). The Red series seems to be a halfway point between the WD Green and WD Black series: like the Green series, they have 4096-byte sectors and IntelliPower (i.e. variable rpm), but they are designed for 24×7 operation and seem to have far more consistent performance—although not quite on par with the Black series. Continue reading “Benchmark: WD Red NAS” »
I’ve acquired a couple more 2 TB Advanced Format drives: a Seagate Barracuda Green (ST2000DL003) and a Samsung SpinPoint F4 EcoGreen (HD204UI, no data sheet available online). Continue reading “More Advanced Format drives: Samsung SpinPoint F4 EcoGreen and Seagate Barracuda Green” »
Just to let you know what the current status is wrt. 4k drives:
It looks like the consensus in the industry (meaning everyone except Western Digital) is to announce dual sector sizes, i.e. 512-byte logical sectors on top of 4096-byte physical sectors.
Ivan Voras has taken the initiative to organize a 4k BoF at BSDCan, although judging from the (private) email exchange on the subject, it’s quite possible that a decision will be made before then. Currently, it looks like we’re moving towards having the low-level driver report a 512-byte sector size and 4096-byte stripe width (and, if necessary, an appropriate offset) to GEOM. This preserves backward compatibility, but announces to GEOM consumers that it is a good idea to do I/O in 4096-byte blocks and align data structures on 4096-byte boundaries. All that remains is then to make sure that those GEOM consumers we care about (particularly ZFS) take advantage of this information.
The situation for WD “Advanced Format” drives is a bit more complex, because they announce 512-byte logical sectors. The only solution I can see is to add a quirk system to the ada driver (and possibly to ata as well, if we still care about it) similar to the ones we have for SCSI and USB devices, and match the model number. I believe /WD\d+[A-Z]+RS/ should match all existing Advanced Format drives with no false positives.
I made a small modification to phybs to verify the function of jumpers 7-8 on the WD Advanced Format drives (see here and here). It is supposed to cause the disk to internally shift every write by one sector, so that a write to sector 63 (where the first partition on a PC normally starts) actually goes to sector 64, which coincides with the beginning of a physical 4,096-byte sector. These numbers confirm this:
count size offset step msec tps kBps 32768 4096 0 16384 78631 34 1666 32768 4096 512 16384 79880 33 1640 32768 4096 1024 16384 73164 36 1791 32768 4096 1536 16384 77727 34 1686 32768 4096 2048 16384 76975 35 1702 32768 4096 2560 16384 74970 36 1748 32768 4096 3072 16384 79379 34 1651 32768 4096 3584 16384 28094 96 4665
The firmware on the disk shifts everything forward by 512 bytes, so all these passes are unaligned except the last one, because 3,584 + 512 = 4,096.