Western Digital Caviar Green 2TB hard drive
Very, very quiet - and very, very capacious
Review Western Digital will break new ground later this month when its 2TB Caviar Green WD20EADS hard drive goes on sale. Seagate packed 1.5TB into its Barracuda 7200.11 drive by using four platters and eight heads, but WD has gone a step better and squeezed 33 per cent more storage capacity into the same space.
WD's Caviar Green 2TB: capacious, most capacious
This marks the 2TB - 1.81TB once formatted - Caviar Green as the first drive to pack 500GB of raw storage capacity on each platter. It’s worth making it clear that this is a single internal SATA hard drive so there’s no jiggery-pokery involved, like packing a pair of RAIDed drives together.
The WD20EADS is a one of WD's GreenPower-branded units, complete with IntelliPower motor control which means that some drives in the product range may have a rotational speed of 5400pm while others may operate at up to 7200rpm. In the case of the 2TB Caviar Green, the notional speed is 5400rpm which results in a latency of 5.5ms rather than the 4.2ms you typically see on a 7200rpm drive.
Variable spin speed
This certainly pays off in terms of the sound and vibration levels. The Green has a reasonable idle noise level of 25dBA that only steps up to 29dBA under load. Those noise ratings fall between a typical 7200rpm drive and a really quiet 5400rpm unit, which is a testament to WD as packing four platters into a drive is a sure-fire way to raise noise levels.
Re: How do folk back these up?
You're right that RAID is not the same as a backup, it just provides protection against data loss due to built-in redundancy.
In some advanced file system like Sun's ZFS or NetApp's offerings, there *is* protection against data being unintentionally corrupted or deleted by the user, application or OS: they are called snapshots. Files and directories referenced by snapshots cannot be deleted until the referring snapshot is deleted -- so there is your protection against loss. Also files/dirs referenced by snapshots cannot be modified -- these file systems employ a method called 'copy-on-write' which means that if a file referenced by a snapshot is modified, the file system creates a copy. If I remember correctly, the common blocks of the two files are not duplicated, to save space, but don't quote me on that :)
A traditional 2-drive mirror is fine until you need, in this case, 2.1 TB. Also traditional mirrors often don't repair files that can't be read -- the file system/RAID controller often just returns the data on the good half of the mirror. However, ZFS also repairs the faulty file on the bad side of the mirror, as indeed it does in any redundant setup: mirror, RAID-Z1 (like RAID 5), or RAID-Z2 (like RAID 6).
For backup/syncing of files that you mention, again, ZFS offers a way of doing this -- with one important difference and huge benefit: you will never lose any data that gets deleted if you use (1) automatic snapshotting (via cron every 30 minutes or whatever), and (2) use 'zfs send/receive' to send an initial full backup and subsequent incremental backups, in which ZFS detects diffs between snapshots and sends only the differences, to another storage pool, which might be on the same machine or a different machine on the LAN/WAN.
These links might be of further interest:
I'll get me coat -- I'm off to the pub... :)
@ mad hacker
yes, quite obviously, that entire paragraph was completely re-written following my rant
it originally talked about dynamically varying the drive speed
a or an
he is right that its entirely down to the sound rather than the specific letter,
the easiest example is:
even though M is not a vowel, in this context it is pronounced:
so its "an em-pee" :P
How do folk back these up?
There seems to be the usual foolish confusion between RAID and backup here.
RAID mirroring (or to a lesser extent RAID5) gives you protection against a hardware failure making data unavailable.
In a full time RAID setup, what protection is there against data being unintentionally corrupted or deleted by the user, by an app, or by the OS? None.
If I had one of these, I'd want two of them, not in any kind of RAID config. And every now and then, I'd use some kind of file sync program to sync the copies of the data. In that way, there is some kind of window when an unintentionally damaged file can be restored from the backup. OK the intact copy may get overwritten if the damage isn't noticed before the next sync point, but only if the sync program doesn't ask for confirmation before overwriting the old copy...
Pricing is good, I'm getting 4.
Just got a firewire drobo and shoved a load of spare old 500GB drives in there to act as a temporary backup for only my most important folders.
However, I've also wanted to be able to keep backups of all my dvds and animation work as well... some of the render outputs (particularly the folders containing 2500+ 1920x1080 TIFF files) are currently too big to be able to backup now that I've had to start making HD content.
Glad to hear it's quiet, too.. would rather not have 4 little rasping dinosaurs spinning away behind my desk when the backups are taking place.
1TB drives were not quite enough to offer a complete solution to all my backups needs, so I didn't bother upgrading.. 2TB does the job nicely.
I can't see myself needing a 4TB drive for a long time... unless something crazy like a new "superHD" standard comes along.