Flushing file writes to disk with 100% reliability
in [Unix Programming]
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From: Peter Olcott on 20 Apr 2010 20:19 "Scott Lurndal" <scott(a)slp53.sl.home> wrote in message news:8drzn.2$XD2.1(a)news.usenetserver.com... > "Peter Olcott" <NoSpam(a)OCR4Screen.com> writes: > >>I will be renting my system from my service provider, thus >>no choices are available for hardware. Both UPS and backup >>generators are provided by my service provider. >> >>SSD have a limited life that is generally not compatible >>with extremely high numbers of transactions. > > Where _do_ you get this stuff? I'm running an Oracle > database > on 64 160-GB Intel SSD's as I write this. The life of any > SSD will > exceed that of spinning media, even with high write to > read ratios, Probably not. http://en.wikipedia.org/wiki/Solid-state_drive Flash-memory drives have limited lifetimes and will often wear out after 1,000,000 to 2,000,000 write cycles (1,000 to 10,000 per cell) for MLC, and up to 5,000,000 write cycles (100,000 per cell) > and the performance blows them all away. I've been > getting upwards Yes. > of 10 gigabytes transferred per second from those drives > (16 raid > controllers each connected to four SSD drives configured > as RAID-0, > 1 TB of main memory). > > scott
From: Peter Olcott on 20 Apr 2010 20:23 "Ian Collins" <ian-news(a)hotmail.com> wrote in message news:836u94Fvj5U5(a)mid.individual.net... > On 04/21/10 06:06 AM, Peter Olcott wrote: >> >> SSD have a limited life that is generally not compatible >> with extremely high numbers of transactions. >> > Not any more. > > They are used in the most transaction intensive (cache and > logs) roles in many ZFS storage configurations. They are > used where a very high number of IOPs are required. > > -- > Ian Collins 100,000 writes per cell and the best ones are fried. http://en.wikipedia.org:80/wiki/Solid-state_drive
From: Ian Collins on 20 Apr 2010 20:51 On 04/21/10 12:23 PM, Peter Olcott wrote: > "Ian Collins"<ian-news(a)hotmail.com> wrote in message > news:836u94Fvj5U5(a)mid.individual.net... >> On 04/21/10 06:06 AM, Peter Olcott wrote: >>> >>> SSD have a limited life that is generally not compatible >>> with extremely high numbers of transactions. >>> >> Not any more. >> >> They are used in the most transaction intensive (cache and >> logs) roles in many ZFS storage configurations. They are >> used where a very high number of IOPs are required. > > 100,000 writes per cell and the best ones are fried. > http://en.wikipedia.org:80/wiki/Solid-state_drive That's why they have wear-levelling. Believe me, they are used in very I/O intensive workloads. The article you cite even mentions ZFS as a use case. -- Ian Collins
From: Peter Olcott on 20 Apr 2010 21:00 "Ian Collins" <ian-news(a)hotmail.com> wrote in message news:8370g2Fvj5U6(a)mid.individual.net... > On 04/21/10 12:23 PM, Peter Olcott wrote: >> "Ian Collins"<ian-news(a)hotmail.com> wrote in message >> news:836u94Fvj5U5(a)mid.individual.net... >>> On 04/21/10 06:06 AM, Peter Olcott wrote: >>>> >>>> SSD have a limited life that is generally not >>>> compatible >>>> with extremely high numbers of transactions. >>>> >>> Not any more. >>> >>> They are used in the most transaction intensive (cache >>> and >>> logs) roles in many ZFS storage configurations. They >>> are >>> used where a very high number of IOPs are required. >> >> 100,000 writes per cell and the best ones are fried. >> http://en.wikipedia.org:80/wiki/Solid-state_drive > > That's why they have wear-levelling. > > Believe me, they are used in very I/O intensive workloads. > The article you cite even mentions ZFS as a use case. > > -- > Ian Collins 5,000 transactions per minute would wear it out pretty quick.
From: Peter Olcott on 20 Apr 2010 21:09
"Ian Collins" <ian-news(a)hotmail.com> wrote in message news:8370g2Fvj5U6(a)mid.individual.net... > On 04/21/10 12:23 PM, Peter Olcott wrote: >> "Ian Collins"<ian-news(a)hotmail.com> wrote in message >> news:836u94Fvj5U5(a)mid.individual.net... >>> On 04/21/10 06:06 AM, Peter Olcott wrote: >>>> >>>> SSD have a limited life that is generally not >>>> compatible >>>> with extremely high numbers of transactions. >>>> >>> Not any more. >>> >>> They are used in the most transaction intensive (cache >>> and >>> logs) roles in many ZFS storage configurations. They >>> are >>> used where a very high number of IOPs are required. >> >> 100,000 writes per cell and the best ones are fried. >> http://en.wikipedia.org:80/wiki/Solid-state_drive > > That's why they have wear-levelling. > > Believe me, they are used in very I/O intensive workloads. > The article you cite even mentions ZFS as a use case. > > -- > Ian Collins 5,000 transactions per minute would wear it out pretty quick. With a 512 byte transaction size and 8 hours per day five days per week a 300 GB drive would be worn out in a single year, even with load leveling. |