I was just wondering if there was a standard frequency of carrying out parity checks?  I've just got my 15TB array finished (at last!) with all content transfered - should I be running a parity check now that all of my data is on there?

 

Thanks

Matt

Most of the people here do it once every 4 weeks. I would say 2-6 week is ok, depends on how often you write to the array... Also, I prefer to do "parity verify" first from unMenu and then decide to correct or not (if there are errors, they might come from defect cables and not necessarily from defect disks).

There's also an unMenu package that will kick off a parity check automatically on the 1st of every month.

Thanks

 

While people are online and posting on this thread, I wonder if someone can give me a quick piece of advice as it's late here in the uk and I need my bed!

 

I'm stuck unmounting the array - I pressed stop and disk1 stills shows as unmounting, which indicates there's a process running (I installed squeezebox earlier though it's not worked).  I wonder if that's stopping it?

 

I've just finished transferring all of my data across so don't want to screw things up, but how can I shut down safely?

 

Thanks in advance  

 

*Edit*:  Just refreshed unMenu and disk1 has finally stopped.  Weird

fuser and lsof are your friends. They will show processes running on that disk and you may grep for them and kill them. There is also a button in unMenu somewhere for lsof (list open files)...

Thanks

 

Back to parity checks, with an 18TB array (although only 10.5TB currently used), how long should I expect a parity check to take?

The size of the array doesn't tell us anything.  It also doesn't matter how full the array is, since a drive full of 0s takes just as long as a drive full of 1s.

 

What we need to know is how many drives you have, how big they are, and how fast they are.  Also if you are using the PCI bus at all, or only mobo/PCIe.

 

Actually, I suppose we could give you a fairly accurate estimate if you just told us the specs of your parity drive, and the info about the PCI/PCIe bus.

Thanks

 

Back to parity checks, with an 18TB array (although only 10.5TB currently used), how long should I expect a parity check to take?

It would also depend on the size of the largest drives.

 

An array of 18 1TB drives on a PCIe bus will take 1/2 the time of an array of 9 2TB drives on a PCIe bus.

The array is 9 drives plus parity and cache - all drives a LP 2TB ones (3 x Samsung F3s and 8 x Seagate LP)

The array is 9 drives plus parity and cache - all drives a LP 2TB ones (3 x Samsung F3s and 8 x Seagate LP)

My array has three 2TB drives and four 1.5TB drives, the monthly parity check was logged as follows:

Nov  1 10:22:32 Tower2 kernel: md: sync done. time=37350sec rate=52302K/sec

 

A bit over 10.3 hours... Yours might take longer, as you have more 2TB drives.  Mine speeds up a little once past the 1.5TB mark  as there are fewer drives involved.

 

Mine is closer to yours in terms of HD's.

 

15x Seagate 2TB LP's:

 

Nov  3 22:55:32 Media kernel: md: using 1152k window, over a total of 1953514552 blocks.

Nov  4 07:27:31 Media kernel: md: sync done. time=30719sec rate=63593K/sec