WD Caviar Black 2TB
Two terabytes of performance HDD
Review The 2TB Caviar Black is the second hard drive we have seen with a capacity of two terabytes. Glance back to our 2008 round-up of 1TB drives, which used three or four platters, and you can see that this is pretty much a doubling of areal density.
Western Digital's Caviar Black 2TB: covered up...
The first 2TB drive we saw was a member of WD’s Caviar Green line-up with an emphasis on environmentally friendly performance. The key here is power draw so the Green drive uses a lowly spin speed of 5400rpm despite the inevitable performance hit.
It’s a different story with the 2TB Caviar Black which has a spin speed of 7200rpm along with a host of other features.
The guts of the Black are similar to the 2TB Green as both models use four 500GB platters with eight read/write heads. However, the extra spin speed has made some changes necessary. For starters, the cache has doubled in size to 64MB. Every drive in the Caviar Black family is described as having "up to 64MB", but to date the only drive we have seen with that much memory is the 2TB - smaller drives have 32MB.
The most dramatic new technology is the twin actuator, and it's currently unique to the 2TB Black. Actually, that’s not quite true as the 2TB Black shares all of its features with the WD RE4, which is an enterprise drive.
The specification of the RE4 is very similar to the Caviar Black in every respect except that it has an MTBF rating of 1.2 million hours while there is no mention made about the expected life of the Black. Both drives have a five-year warranty. The other difference is that the RE4 is intended for use in Raid and as a result the TLER (Time Limited Error Recovery) is much lower. A desktop drive will typically attempt to recover bad sectors for 15 seconds while we understand that the RE4 will quit after seven seconds.
> CRC checks in the filesystem are a nice feature but they are only checks, they are not error correcting at all just error detection
You are wrong. ZFS detects *and corrects* errors. The 256 bit block checksums are compared with the data read back during a file read or scrub operation, and if an error is detected it is corrected using parity data in redundant vdevs.
If you don't believe this, try reading the ZFS tech info available -- look under 'self-healing'.
"The real annoyance is that Windows and Mac OS X both insist on measuring in GiB, but use the "GB" suffix like they're just trying to confuse you. Hence the icon."
Yeah, both major operating systems are trying to confuse you, not the HDD manufacturers. *sigh*.
Windows and Mac OS X have been *correctly* reporting in "MB" and "GB" since before MiB and GiB were even invented.
MB = megabyte (2^20 bytes)
GB = gigabyte (2^30 bytes)
MiB = Men in Black, a movie starring the Fresh Prince
GiB = Girls in Black, a little known blaxploitation sequel
"You can buy 1TB 2.5" drive ---- where???
I think the statement "You can buy 1TB 2.5" WD drive" is incorrect. 1TB 2.5" drive is still only a WD marketing dream and exists only as HTML page on Western Digital site. I cannot buy it neither from WD site nor from any other channel. Only 500GB drives on stock, same as half a year ago.
I think Western Digital managers developed and excellent way to get bonuses. If the product is not ready on time - just place nice description on web page, and you can put a plus sign that it is "released". When, in reality, half a year will pass until customers are able to buy the product.
I suggest to clearly mark all the pages where product is not yet on sale. I.e.: "Future product. Estimated availability date - December 2009."
You can have it all with OpenSolaris and ZFS...
Leo Waldock writes, "This is thoroughly good news but of course it’s the combination of performance allied to the colossal 2TB capacity that catches the eye. That said, the formatted capacity is a ‘mere’ 1863GB."
Under OpenSolaris with ZFS - you will have more of the 2TB potential, if you are running with redundancy, since ZFS can perform the error correction for you, instead of being done on the disk drive... no sense in doing the error correction twice and losing the space twice when the loss of space in CRC's is redundant...
Generally wikipedia is not a place to go quoting. At the same time if you read what it did say, the filesystem overhead is less than 1% of the space. The difference between 2000GB and 1863GiB is a lot more than 1% (6.8% in this case). So it has nothing to do with the filesystem overhead or formatting or anything else, it is simply a matter of the HD makers and Microsoft using different units. Back when harddisks were measured in MB the difference was smaller and many people just claimed it was the overhead of the filesystem, even though it wasn't true then either. Now that we are starting to see rather large differences people actually start to really notice it. If you were to convince windows to show you the size in bytes instead of GiB then you would still have a capacity of the filesystem even with the filesystem overhead of very close to 2000000000000 bytes.