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#11
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Malcolm Weir wrote:
On Sat, 25 Sep 2004 03:30:25 GMT, "Ron Reaugh" wrote: snip In the event of a server failure the only way to ensure the integrity of your data is have battery backed up cache. Toto, the following is why ignoring this Ron "character" is good advice: The only way to ensure that the data held at that instant in the cache(could be none) is not lost is to have some sort of battery support. A UPS is often sufficient. Losing some data in the cache does NOT mean that you have lost all integrity...just a small amout of the most recent data. snip Without meaning to take sides, would someone mind explaining a situation whereby a general UPS would not be sufficient to protect data integrity in the event of a power failure? (and I don't mean things like the UPS catching fire, though I do understand this is a very real possibility). -- Meurig |
#12
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"Meurig Freeman" wrote in message ... Malcolm Weir wrote: On Sat, 25 Sep 2004 03:30:25 GMT, "Ron Reaugh" wrote: snip In the event of a server failure the only way to ensure the integrity of your data is have battery backed up cache. Toto, the following is why ignoring this Ron "character" is good advice: The only way to ensure that the data held at that instant in the cache(could be none) is not lost is to have some sort of battery support. A UPS is often sufficient. Losing some data in the cache does NOT mean that you have lost all integrity...just a small amout of the most recent data. snip Without meaning to take sides, would someone mind explaining a situation whereby a general UPS would not be sufficient to protect data integrity in the event of a power failure? A micro Weir meteroid hits the UPS wire because its so far away from the RAID controller maybe. |
#13
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Ron Reaugh wrote:
"Meurig Freeman" wrote in message ... Malcolm Weir wrote: On Sat, 25 Sep 2004 03:30:25 GMT, "Ron Reaugh" wrote: snip In the event of a server failure the only way to ensure the integrity of your data is have battery backed up cache. Toto, the following is why ignoring this Ron "character" is good advice: The only way to ensure that the data held at that instant in the cache(could be none) is not lost is to have some sort of battery support. A UPS is often sufficient. Losing some data in the cache does NOT mean that you have lost all integrity...just a small amout of the most recent data. snip Without meaning to take sides, would someone mind explaining a situation whereby a general UPS would not be sufficient to protect data integrity in the event of a power failure? A micro Weir meteroid hits the UPS wire because its so far away from the RAID controller maybe. Damn, hadn't considered that one... anyone recomend any good websites selling meteroid sheilding? -- Meurig (http://xboxmods.meurig.com - modded xbox for sale) |
#14
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"Meurig Freeman" wrote in message ... Ron Reaugh wrote: "Meurig Freeman" wrote in message ... Malcolm Weir wrote: On Sat, 25 Sep 2004 03:30:25 GMT, "Ron Reaugh" wrote: snip In the event of a server failure the only way to ensure the integrity of your data is have battery backed up cache. Toto, the following is why ignoring this Ron "character" is good advice: The only way to ensure that the data held at that instant in the cache(could be none) is not lost is to have some sort of battery support. A UPS is often sufficient. Losing some data in the cache does NOT mean that you have lost all integrity...just a small amout of the most recent data. snip Without meaning to take sides, would someone mind explaining a situation whereby a general UPS would not be sufficient to protect data integrity in the event of a power failure? A micro Weir meteroid hits the UPS wire because its so far away from the RAID controller maybe. Damn, hadn't considered that one... anyone recomend any good websites selling meteroid sheilding? Weir-d must know one. |
#15
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Meurig Freeman wrote in
: Without meaning to take sides, would someone mind explaining a situation whereby a general UPS would not be sufficient to protect data integrity in the event of a power failure? (and I don't mean things like the UPS catching fire, though I do understand this is a very real possibility). It's always safe to take sides with the people disagreeing with Ron. There are a lot of other things that can go wrong, besides the power failing. UPS, PSU or cable failures (like your cleaning lady hitting the cable with her broom) will all take out your non-battery-backed cache. In any case, i'd always go for battery-backed (write) cache or no cache at all. -- /Jesper Monsted |
#16
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Meurig Freeman wrote in
: Damn, hadn't considered that one... anyone recomend any good websites selling meteroid sheilding? Try the people who sold Ron his tin foil hats. -- /Jesper Monsted |
#17
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In article ,
Meurig Freeman wrote: Malcolm Weir wrote: On Sat, 25 Sep 2004 03:30:25 GMT, "Ron Reaugh" wrote: snip In the event of a server failure the only way to ensure the integrity of your data is have battery backed up cache. Toto, the following is why ignoring this Ron "character" is good advice: The only way to ensure that the data held at that instant in the cache(could be none) is not lost is to have some sort of battery support. A UPS is often sufficient. Losing some data in the cache does NOT mean that you have lost all integrity...just a small amout of the most recent data. snip Without meaning to take sides, would someone mind explaining a situation whereby a general UPS would not be sufficient to protect data integrity in the event of a power failure? (and I don't mean things like the UPS catching fire, though I do understand this is a very real possibility). Your system power supply fails (not uncommon, actually). Some bozo knocks the system power cord loose. Someone hits the reset switch or power switch on the front of the machine, whether accidentally or through lack of understanding. The operating system crashes and reboots the machine without politely telling the RAID card to flush its cache. A UPS won't save your butt in any of these cases. Battery backup on the RAID card will. -- Thor Lancelot Simon But as he knew no bad language, he had called him all the names of common objects that he could think of, and had screamed: "You lamp! You towel! You plate!" and so on. --Sigmund Freud |
#18
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"Meurig Freeman" wrote in message ... .... Without meaning to take sides, would someone mind explaining a situation whereby a general UPS would not be sufficient to protect data integrity in the event of a power failure? (and I don't mean things like the UPS catching fire, though I do understand this is a very real possibility). Ever seen your PC reboot on a power glitch that your more-than-adequately-sized home UPS should have ridden through without notice? I have. And this doesn't happen only with home units: it has been known to happen with server-room UPSs (though of course should be far less common there). The bottom line is that if you're going to use RAID-style redundancy, any non-disk elements of the system that are trusted to hold supposedly 'stable' data should be just as reliable as the redundant disks themselves. This means that you'd need to mirror cached data in double ECC caches, using separate power supplies and UPSs (or cache-level batteries), to obtain similar levels of availability. - bill |
#19
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"Jesper Monsted" wrote in message 4.163... Meurig Freeman wrote in : Without meaning to take sides, would someone mind explaining a situation whereby a general UPS would not be sufficient to protect data integrity in the event of a power failure? (and I don't mean things like the UPS catching fire, though I do understand this is a very real possibility). It's always safe to take sides with the people disagreeing with Ron. Only for the trolls. There are a lot of other things that can go wrong, besides the power failing. UPS, PSU or cable failures (like your cleaning lady hitting the cable with her broom) Sounds like a Weir micrometeroite...rumor has it that they ride brooms. |
#20
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"Thor Lancelot Simon" wrote in message ... In article , Meurig Freeman wrote: Malcolm Weir wrote: On Sat, 25 Sep 2004 03:30:25 GMT, "Ron Reaugh" wrote: snip In the event of a server failure the only way to ensure the integrity of your data is have battery backed up cache. Toto, the following is why ignoring this Ron "character" is good advice: The only way to ensure that the data held at that instant in the cache(could be none) is not lost is to have some sort of battery support. A UPS is often sufficient. Losing some data in the cache does NOT mean that you have lost all integrity...just a small amout of the most recent data. snip Without meaning to take sides, would someone mind explaining a situation whereby a general UPS would not be sufficient to protect data integrity in the event of a power failure? (and I don't mean things like the UPS catching fire, though I do understand this is a very real possibility). Your system power supply fails (not uncommon, actually). Some bozo knocks the system power cord loose. Someone hits the reset switch or power switch on the front of the machine, whether accidentally or through lack of understanding. The operating system crashes and reboots the machine without politely telling the RAID card to flush its cache. A UPS won't save your butt in any of these cases. Battery backup on the RAID card will. Clueless jibber. So batteries on the cached controller suddenly make the OS polite? Where's the one about space aliens in your list? It's so easy to dismiss these zealots. |
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