Re: LSI MegaRAID SAS 9240-4i hangs system at boot
On Thu, 14 Jun 2012 08:38:27 -0500
Stan Hoeppner <stan@hardwarefreak.com> wrote:
> On 6/14/2012 4:51 AM, Ramon Hofer wrote:
>
> >> These commands don't match the pastebin. The pastebin shows you
> >> creating a 4 disk RAID5 as /dev/md0.
> >
> > Really :-?
>
> That kind of (wrong) analysis is one of the many outcomes of severe
> lack of sleep, too much to do, and not enough time. ;) Having 3
> response/reply chains going for the same project doesn't help either.
> We share fault on that one: you sent 3 emails before I replied to the
> first. I replied to all 3 in succession instead of consolidating all
> 3 into one response. Normally I'd do that. Here I simply didn't
> have the time. So in the future, with me or anyone else, please keep
> it to one response/reply. :) Cuts down on the confusion and overlap
> of thoughts.
Ok I will.
I'm still learning the code of conduct for mailing lists ;-)
I then start right now.
First of all I tried to set the raid5 with the WD 20EARS and didn't
have much luck. They led to fail events when mdadm builds the array.
They "worked" in my Netgear NV+ with very low r/w rates <5 MB/s (which
I now assume is because of the disks.
That's why I'm already thinking of buying new disks.
I have found these drives at my local dealer (the prices are in Swiss
Francs).
2 TB:
- Seagate Barracuda 2TB, 7200rpm, 64MB, 2TB, SATA-3 (129.-)
- Seagate ST2000DL004/HD204UI, 5400rpm, 32MB, 2TB, SATA-II (129.-)
3 TB:
- Seagate Barracuda 3TB, 7200rpm, 64MB, 3TB, SATA-3 (179.-)
I think the Seagate Barracuda 3TB are the best value for money and I
didn't find any problems that could prevent me from using them as raid
drives.
Btw. When I tried to set up the WD20EARS mdstat told me that the
syncing would take about 6 hours. Hopefully the Barracudas have at
least the same rate. Then the process would be finished on maybe less
than 9 hours. This seems to be acceptable for my case.
> Also, please note that with 2TB drives, the throughput will decrease
> dramatically as you fill the disks. If you're copying over 3-4TB of
> files, a write rate of 20-30MB/s at the end of the copy process should
> be expected, as you're now writing to the far inner tracks, which have
> 1/8th or so the diameter of the outer tracks. Aerial density * track
> (cylinder) length * spindle RPM = data rate. The aerial density and
> RPM are constants.
So if I see low rates in the future I can add a new raid5 and get
higher throughbput again because the linear raid would write first to
the new array?
> > Now I only have to setup the details correctly.
> > Like the agcount...
>
> Like I said, it may not make a huge difference, at least when the XFS
> is new, fresh. But at it ages (write/delete/write) over time, the
> wonky agcount could hurt performance badly. You balked at that
> 20MB/s rate which is actually normal. With XFS parms incorrect, a
> year from now you could be seeing max 50MB/s and min 5MB/s. Yeah,
> ouch.
Another reason to set it up properly now :-)
> > You really were an incredible help!
>
> When I'm not such a zombie that I misread stuff, yeah, maybe a little
> help. ;)
No really. The adventure of enlarging my media server would have ended
in total frustration!
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