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Comment Re:BTRFS is getting there (Score 3, Informative) 266

The features you list as "specific" to zfs exist in btrfs. btrfs can have dedicated parity drives or you can spread the data and parity across multiple drives in any order or pattern you would like.

The write hole in btrfs is AFIAK also present in zfs and listed as a risk of a power failure during write on a raid pool with COW filesystems. This risk is that loss of power during write can result in multiple different parity blocks for the same data and that in such an instance the filesystem cannot identify the correct data or parity (depending on the order you write them) and there are only a few solutions to this that involve resorting to a known good (older) copy and result in lost data (from the write).

IIRC this is a listed risk in the FAQ for ZFS. Just as the same write hole risk exists in btrfs. Also IIRC ZFS takes the path of writing parity before data such that it will lose new data rather than risk a corruption of existing parity blocks. Whereas, again IIRC btrfs COW's the new data then COW's the parity block which risks inconsistent parity but at less risk of data loss (as parity can be recomputed).

Two different solutions to the same problem that is intrinsic to COW filesystems with parity data. Neither is particularly better IMO as both run the risk of data loss in an extreme event. Though such events are rare.

Comment Re:BTRFS is getting there (Score 1) 266

My understanding is that the it does take advantage of COW. The problem is your parity has two copies, and you have two copies of the data that may or may not match the parity because it lost power during the write. This is why they call it a write hole because the algorithm can't be sure which copy of the written data is the right one because their are two copies of parity data as well. It's a tricky problem that's going to need either some pretty smart algorithms to sort out which copy is the right one or a prompt to the user to identify the correct file.

On the other hand IIRC zfs suffers from a similar problem with power loss and it's one of the reasons zfs is recommended to have a battery backup to allow a clean shutdown. It is my understanding this is a general design problem with COW filesystems that really hasn't been completely solved yet. In that if you have a corrupted write with parity data it becomes difficult for the computer to identify the correct data and parity because it has multiple copies of each and some may or may not be corrupt. It's just a really tough problem.

Comment Re:Outsider (Score 1) 173

You don't understand what insider trading is. I doubt you've ever even bought stocks. Insider trading has a VERY strict definition within the law, so strict in fact that insider information passed 2 degrees away from the source which resulted in a prosecution was recently thrown out by the supreme court because it didn't meet the material rewards test the law requires.

This isn't insider trading. It's filthy and dirty and throws the whole industry into disrepute but it's not currently illegal. Though if the industry doesn't stamp this out right quick I wouldn't be surprised to see congress "fix" it for them.

Comment Re:BTRFS is getting there (Score 1) 266

Raid support has been built into btrfs for ages now. It's been rock stable for me for over a year with an 8 disk array in raid 5 configuration. But the simplicity with which you can add and subtract drives, parity drives and others makes btrfs a total winner IMO.


Comment Re:BTRFS is getting there (Score 1) 266

There is no problem with Raid 5 on Btrfs. I've been running a raid 5 on btrfs for more than a year. I'm not sure why ZFS fanboi's always resort to lying about the btrfs features and support, if it's just laziness on their part or they are astroturfing.

ZFS may be stable, but it development is relatively frozen and btrfs is in many ways better but has lagged in development. This is probably because Oracle was the primary backer of btrfs before they bought Sun and there just aren't enough developers working on btrfs but that doesn't mean it's still not advancing and improving every year. I personally like btrfs a lot more than zfs because some of the features such as shrinking and growing pools is a MAJOR feature that ZFS lacks while btrfs supports all the zfs features that I care about.

But either way, if you are going to talk about features or aspects of btrfs at least make sure your information is current for gods sakes!

Comment Re:Just (Score 1) 186

See the other reply. Solar installed right now is about $2 a watt and it's continuing to fall. It's got a ROI of around 3 years in most of the US right now. That's a damn good investment, let alone power for your home. And the best part is after you pay the panels off your power is essentially free for a guaranteed 25 years (panel warranty).

Comment Re:Just (Score 1) 186

Batteries are rapidly falling in price. Just 2 years ago you would have paid $500kw/h of storage. The price is down to almost $250 currently. Once it reaches $100 it's actually going to be cheaper to use batteries and solar panels than it will be to hook up to the grid.

I wouldn't be invested in power utilities right now given that if they don't manage the renewable transition well they are likely to be put right out of business.

Comment Re:How do they define GM? (Score 1) 325

DDT was and is safe, for humans. But we don't eat insects that have died from it.

DDT is responsible for the elimination of malaria and several other diseases from the US. Most people have no idea of that because DDT has been so disparaged and the elimination happened more than a generation ago. In the early part of the 20th century Americans in the south routinely died of tropical diseases, malaria and others. DDT eliminated those diseases from the US by killing the hosts, disease carrying mosquitoes. It's for this reason that DDT is actually still allowed to be used in the US, under circumstances where diseases are being spread by mosquitoes again and other pesticides are ineffective. It's also still made a sold to regions that suffer from these diseases.

"From there to here, from here to there, funny things are everywhere." -- Dr. Seuss