Warren Shane Collins, 54, who pleaded guilty to wounding with intent to cause grievous bodily harm, has been sentenced to a maximum prison term of seven years and will be eligible for parole after three-and-a-half years.

Sentencing him in the NSW District Court on Tuesday, Judge Chris Craigie said he took into account the "hours of utter terror experienced by the victim as he lay bleeding and facing what he believed was imminent death".

But the judge was satisfied that Warren Collins was " floridly mentally ill at the time" of the attack.

On July 26 2018 Ben Collins flew from Melbourne to visit his brother, who was adopted at birth, in his Sydney home.

After Ben downloaded YouTube onto Warren's phone so he could listen to music, his brother became suspicious he was trying to hack into the device to steal his cryptocurrency, according to the facts.

He also believed his brother was spiking his food with the drug ice, a substance he had been using in the weeks prior, and which caused him paranoid thoughts.

The pair continued to fight over the mobile phone issue for a week before Warren called his sister saying he was "kicking him out" and would pay for his ticket home.

Meanwhile, Ben had also been trying to call her to say he was disturbed by his brother's mental state, and that he no idea what had happened.

"I'm getting the next cheap flight out tomorrow," the court heard.

But 5am that day Warren retrieved a small wooden-handled knife from his cupboard, and stabbed his brother multiple times while he slept in his living room.

After waking and asking "what are you doing?", Warren replied "I'm stabbing you, I'm going to kill you... because you stole all my Bitcoin".

For two hours Ben lay incapacitated on the mattress from nine stab wounds, bleeding and struggling to breath, continually pleading for his phone saying he was dying.

As Warren sat on a nearby couch, his brother told him "you're killing me for nothing".

After saying "I'm going to die too, I'm not going to go to jail," Warren stabbed himself in the stomach several times.

After about two hours he handed Ben his phone to call emergency services, saying he "didn't have long".

Police arrived shortly after and saw Warren drink a black bottle containing hydrochloric acid twice, before spluttering and falling to his knees.

Following the "ferocious attack" Ben suffered life multiple life-threatening injuries, and required numerous surgeries to fix multiple lacerations to his neck and back.

Warren later testified that he was "very, very sorry for what I have done to him".

Warren's permanent self-inflicted injuries mean he will forever be fed through a nasal tube into a digestive tract that has been destroyed from the acid he ingested.

In October 2019 he was formally diagnosed with schizophrenia, an underlying condition that medical experts say was set off by his concentrated use of ice.

He will be eligible for release in February 2022.

Australian Associated Press