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visits member for 5 years, 8 months
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I am weasel!

all of the hats, all of the hats...


Mar
23
comment Someone uploaded index.php into my ubuntu server, I don't know how?
Weak passwords, sql injection, buggy plugin, trojan. There are many possible ways, a whole stack exchange worth security.stackexchange.com. You have given no info to narrow that down. If you don't understand how to secure a server you need to employ someone who does. There is not a magic checkbox to tick and it becomes secure.
Mar
20
comment Two DHCP servers in one network
@Sven I can't find a canonical one, maybe this? serverfault.com/questions/325023/dual-isps-load-balancing/…
Mar
20
comment Two DHCP servers in one network
@Sven although it matches their title, don't think this dupe matches what they really asked. Would be better as a dupe of a multiple gateways/ISPs question.
Mar
16
comment Why is RAID 1+6 not a more common layout?
Since you are proposing an untested theory that defies conventional wisdom why don't you detail your setup where you have shown it to work? I would guess that since your maths differs from every other source on this subject as well as real world tests the reason why it doesn't work is that your maths is wrong.
Mar
15
comment Why is RAID 1+6 not a more common layout?
Please state your source for this information. A practical test with large or tiny writes does not concur with the performance you have suggested.
Mar
13
comment Building one big filesystem with JBOD and ZFS
you almost certainly don't actually want one big filesystem
Mar
12
comment Why is RAID 1+6 not a more common layout?
You stated based on your calculations that RAID1+6 has the same write throughput as RAID10 with triples. In reality RAID1+6 has not even remotely the write throughput of RAID10 so your calculations or the assumptions they are based on are wrong. I was trying to help you understand why, if you refuse to listen then we might be wasting our time but it is you who is wasting it.
Mar
12
comment Why is RAID 1+6 not a more common layout?
I think basically you have read someone generalising the throughput calculation and are trying to apply it as if it is a rule when it isn't. And it certainly doesn't work for nested situations that are multiplicative.
Mar
12
comment Why is RAID 1+6 not a more common layout?
you don't get 4 chunks written for the price of one. Throughput per drive is dependent on the amount of data, so that has already been cancelled out. The number of reads does not depend on chunksize, it is always required to calculate parity. It might be helpful if you linked where you are getting these ideas from.
Mar
12
comment Why is RAID 1+6 not a more common layout?
I think you are quoting something without understanding it. What you are saying specifically about write amplification is technically correct only because RAID6 requires 3 writes the same as a 2nd mirror. But what you are missing is that parity in RAID6 also requires reads. The disk IOs limit throughput, not just the disk writes.
Mar
12
comment Why is RAID 1+6 not a more common layout?
no writing 4 chunks at once does not magically increase drive throughput by 4 :) Less than optimal chunksize can only lower throughput from the theoretical maximum.
Mar
12
comment Why is RAID 1+6 not a more common layout?
no that is incorrect. Each RAID6 write takes 6 IOs and each RAID1 write takes 2 IOs, these are multiplicative. So in RAID 1+6 each write will take 12 IOs, for RAID 10 is it 2 IOs. Write throughput on 12 drives will be 1x for RAID1+6 and 6x for RAID10!
Mar
11
comment Why is RAID 1+6 not a more common layout?
Your thoughput calc doesn't seem to have taken into account the write amplification to create the parity.
Feb
25
comment Duplicate MAC address, can be blocked?
If someone is spoofing a mac address on a physical network they wouldn't need to make a seperate dhcp request.
Feb
19
comment How to protect against loss of server on a budget
@warren the difference is how that is implemented. Do they just have a bunch of VMs on a physical machine or do they have a bunch of VMs on a pool of physical machines.
Feb
14
comment Removing an (apparently) infinitely recursive folder
The fact that it wasn't actually infinately recursive but just very deep is significant and was a major red herring assumption.
Feb
13
comment How to protect against loss of server on a budget
@MichaelHampton that is not even remotely what I was suggesting. A company hosting VPS's for hundreds of clients can spread them amongst redundant hardware rather than simply put a bunch of them on a single physical server and cross their fingers.
Feb
13
comment How to protect against loss of server on a budget
High availability is readily available even for small clients from good providers. They get economy of scale.
Feb
13
comment How to protect against loss of server on a budget
Choose a host who is big enough to use virtualisation. Hardware failures mean your VPS will transparently transition to alternate hardware. This shouldn't really be any more expensive.
Feb
11
comment How to build an energy efficient small office server?
@n1000 you arn't in the realms of reality. 3 disks in a raid takes ~33W active 20W idle without any other hardware. You think you can do a better job than experienced hardware engineers, be my guest and waste your time. If you want to lower the life of your hardware turn it off when you leave the office.