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server offline suddenly

Drhemi

Well-known member
⭐️⭐️PATRON⭐️⭐️
I am having an issue with one of my K servers. The 1U server is offline. According to the K Store, it has been offline since Saturday. I have rebooted it and unplugged it for over a minute and then rebooted, all to no avail. The front display starts blue on power up, lasts for 13 or 14 seconds and then goes out. This repeats about 3 times and then there is a short blue flash or sometimes more from the display. Then it cycles through the same again. There is a soft ?whirring? sound during the longer blue light times as if the unit were trying to power up but cannot (my interpretation, could be way off). We did have a brief power interruption here this week, but it was after the problem had already started. All units are plugged into my big APC UPS.

I have contacted my dealer, but in the meanwhile I was wondering if anyone had any helpful ideas as to what may be happening and what else I could try from my end.

Thanks,

Wayne
 
Unfortunately, this could be a power supply issue, only resolved by having the PS replaced (if it is the problem). Your dealer can have K take a look at it in the logs to see if that helps define the problem. Sorry.



Jim
 
Thanks,

Rusty from K support concurs with the likelihood of it being a power supply issue. A replacement part is being sent to my dealer which will hopefully resolve this with all my data unharmed.

Wayne
 
I'm pretty confident your data is all fine. It's one of the strengths of the Kaleidescape file system... practically impossible to damage your files even in a hardware failure.
 
I'm pretty confident your data is all fine. It's one of the strengths of the Kaleidescape file system... practically impossible to damage your files even in a hardware failure.

Thanks, Josh.

The part arrived today, so I hope to get it up and running again tomorrow. I'll keep my fingers crossed that this is the solution.

Regards,

Wayne
 
Server back online!

I replaced the power supply using the excellent kit and instructions from K and my 1U server is back "good as new." All data is intact. I am glad it was not more serious (and expensive).

Wayne
 
Glad to hear it!
 
That's great Wayne!:) (Although I don't know anyone that has ever had to re-import their content, I'm sure it would a pain......unless all of your content came from the K Store.)




Jim
 
Well, you do now! Or, once you get to know me, anyway. :) I had to do it for one of my customers with a 3U, because they lost two drives in an eight drive group that was loaded up with content. First one drive, and then the second in relatively quick succession, died before I received the first replacement and could get it installed. Bad day, that. Fortunately, I had access to a Bulk Loader. It still took a LONG time to get the movies and TV series and music all back in that server.
 
That's too bad, and likely no fun, but it can happen (as you know), I've just not personally encountered anyone that lost it all.

He's lucky you had a BL to help with the process!



Jim
 
So the second one failed even before the hot spare rebuilt? That's crazy.

Kevin D.
 
I guess. not sure. Since two drives went down in short order, and the system was full (literally the system showed it had room for O Blu-ray, 1 DVD, or a few CDs) I guess the second drive failure doomed it, whether it was during a rebuild or after. Since the replacement 3U had 4TB drives, it doubled their previous capacity, so unless they fill it that much again before expansion, it could survive a loss or two. I think it was the coincidence of being FULL and having two sequential failures that did the trick that time.
 
I thought the 3U could servive 2 drive failures (1 hot spare; equivalent of 1 drive for RAID). Are there special cases where this is not the case? After one drive failure is the data being rebuilt so that a second failure during this process causes data loss?

John
 
The only thing I think makes that not work out is if the drives are full of data, as I mentioned, and as in this case. If you lose one drive, the spare takes over, but I guess there's no safety net if a second drive goes and they are all full of data. If you have enough room left, I think you'd still be fine, you just wouldn't be able to import any more content until a repair was effected.
 
In most situations, the 3u can only survive 1 drive failure at a time even with a hot spare. When the drive fails, the hot spare will immediately replace the failed drive but the data from the failed drive has to be rebuilt on the hot spare. If a second drive fails during the rebuild the filesystem can't recover on its own and data loss will occur.

The exception to this rule is the failure of an empty drive. If a drive that has never had any data written to it fails, kOS will simply remove the drive from the file system and the system will remain healthy albeit with diminished capacity.
 
It can survive two sufficiently-timed concurrent failures, but amount of space left in the array probably doesn't mean anything (unless that's a quirk of K versus the general RAID variants.) Otherwise it could theoretically survive up-to 12 concurrent failures. The more paranoid of us could probably check to make sure all the drives aren't coming from the same manufacturing batch when bringing a bunch online, but I suspect K's processes would have the side-effect of randomizing them enough once they've been available for a little bit.
 
In most situations, the 3u can only survive 1 drive failure at a time even with a hot spare. When the drive fails, the hot spare will immediately replace the failed drive but the data from the failed drive has to be rebuilt on the hot spare. If a second drive fails during the rebuild the filesystem can't recover on its own and data loss will occur.

The exception to this rule is the failure of an empty drive. If a drive that has never had any data written to it fails, kOS will simply remove the drive from the file system and the system will remain healthy albeit with diminished capacity.

Thanks - this makes sense.

Does anyone know how long it takes to rebuild to the hot spare once a drive failure occures (assuming the current 4TB drives)?

John
 
... but amount of space left in the array probably doesn't mean anything (unless that's a quirk of K versus the general RAID variants.) Otherwise it could theoretically survive up-to 12 concurrent failures.

I prefer to think of it as a "feature" rather than a "quirk" :)
Remember that KRAID is different from bog standard RAID and has a number of enhancements (that's why, for instance, you can mismatch disk capacities in the filesystem).

A brand new, 14 disk filesystem (including the hot spare) absolutely could survive 12 concurrent failures as long as the 12 drives that failed had not had any data written to them yet. As each drive failed, the filesystem capacity would be reduced by the size of the cartridge that failed.
 
.....Does anyone know how long it takes to rebuild to the hot spare once a drive failure occures (assuming the current 4TB drives)?

John


Rebuild time can vary, but typically 24 - 48 hours (Replication of content between Servers is slightly different at about 1TB per day, just fyi.)



Jim
 
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