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kiomon
JBOD
Joined: 29 Dec 2009
Posts: 1
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 Posted: Tue Dec 29, 2009 2:03 pm Post subject: Help w/ Promise LUN Set-up (Have read APPLE scripts) |
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Hi all,
I am about to configure my LUNs for an XSAN install. We have 3 E+J units. I have to scripts from Apple. But wondering if there is a way to be more efficient. I am making a single volume. If I use the scripts from APPLE, i would end up with a 60TB Main Volume (12x 6 Drive RAID5 Luns), and 10TB Audio/Scratch Volume (5 X 3 Drive RAID5 LUNs), and 7TB of Spares. I am fine with the number of spares, but I am wondering if there is a better use of that 10TB of scratch drives or a better overall approach.
Let me know, I want to run scripts today on the drives!
Randall |
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abstractrude
Xsan Master
Joined: 13 Mar 2008
Posts: 860
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| Posted: Tue Dec 29, 2009 2:41 pm Post subject: |
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| you should read through other posts here about configuring your disks. i dont know why apple has the scratch space. the way i usually do it with promise e+j is 7 disk raid 5's 2 hot spares per chassis. |
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brianwells
Xsan Master
Joined: 22 Oct 2008
Posts: 80
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| Posted: Tue Dec 29, 2009 8:06 pm Post subject: Using 7-disk RAID5 LUNs |
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We configured a set of Promise VTrak E+J units with 7-disk RAID5 LUNs as shown in the image below. This gives us 2 spares and 2 disks for a metadata LUN. If you contact Promise support, they should be able to help you with a suitable script (or you can do it yourself  )
I just received a new J-class VTrak that will added to the second E-class subsystem. These will be configured with 7-disk LUNs just like the first set.
-- Brian Wells
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JesusAli
Xsan Master
Joined: 25 Jul 2008
Posts: 151
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| Posted: Mon Jan 04, 2010 1:11 pm Post subject: |
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I just had a situation where TWO disks in one chassis reported themselves as missing. If I had only ONE spare I would have been screwed!
I recommend following the Promise/Apple recommendations for that reason.
At the least, I would put 1 global spare in each chassis, in case something went wrong with inter-chassis communications.
Also, I've read that it is important to have the MDJ LUN be the first (or no later than the 2nd) LUN to ensure optimal performance. |
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brianwells
Xsan Master
Joined: 22 Oct 2008
Posts: 80
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| Posted: Sat Jan 09, 2010 1:57 pm Post subject: |
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| JesusAli wrote: | I just had a situation where TWO disks in one chassis reported themselves as missing. If I had only ONE spare I would have been screwed!
I recommend following the Promise/Apple recommendations for that reason.
At the least, I would put 1 global spare in each chassis, in case something went wrong with inter-chassis communications. |
There is obviously a measure of greater risk in having only two spare disks instead of the four spares in the Apple configuration. However, we feel that with our configuration the increase in risk is very small compared to the benefit of having 20% more usable storage.
The failure of a JBOD IO module or SAS cable connecting the enclosures seems unlikely. Even if such a failure occurred, the connected RAID controller should fail over. The remaining RAID controller would continue to have access to the spare drives in the second enclosure in the event of a disk failure.
One failure we have seen with the VTrak systems is what appeared to be defective AAMUX adapters on certain drives. In one new unit, we had four drives with rapidly increasing link count errors. Promise quickly replaced these drives before any real problems occurred and we now regularly track the link count errors.
Our VTrak systems are constantly monitored and replacement parts are on hand to reduce the chance of downtime in the event of hardware failure. We also have a backup procedure in place so that all the critical data is copied to computer tape or other storage systems.
So we are very confident with our VTrak configuration.
| JesusAli wrote: | | Also, I've read that it is important to have the MDJ LUN be the first (or no later than the 2nd) LUN to ensure optimal performance. |
Although not indicated in the diagram I posted, the metadata LUN is the first logical drive on the VTrak. We configured the metadata LUN before the others since that is what Apple's script does. The physical drives used for each LUN were selected so that it would be easy for a technician to see how they were organized ...it also looks nice in the diagram
I am not aware that selecting a certain physical drive for a LUN has any impact on performance, but since you read that the order of the LUNs matters it would probably be a good thing to investigate. I would be interested if you are able to locate the information you had read on LUN ordering and if you have found anything related to physical drive selection.
Thanks,
-- Brian Wells |
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JesusAli
Xsan Master
Joined: 25 Jul 2008
Posts: 151
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| Posted: Mon Jan 11, 2010 11:29 am Post subject: |
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Hey Brian. The information I had read was most likely from a post here on Xsanity. Probably in the Promise Forum. Unfortunately, I can't be more specific than that.
But I do believe the thrust of the thinking was that LOGICAL disk position is what mattered, not PHYSICAL position. |
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lucasnap
Xsan Master
Joined: 05 Oct 2006
Posts: 107
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| Posted: Tue Jan 12, 2010 9:58 am Post subject: |
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Just a question on this topic.
Is it possible to split the metadata-mirror over the V-TRAK E and J and keep for each chassis one spare?
In this case you would have less change that a LUN would be over multiple chassis. (except for the metadata LUN of course but that is only a mirror.. Not a fast LUN).
I know, 6 x video LUN is not a smart count. Working on that.
Thanks,
Lucas |
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JesusAli
Xsan Master
Joined: 25 Jul 2008
Posts: 151
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| Posted: Tue Jan 12, 2010 1:31 pm Post subject: |
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LUN's, of course, can span chassis.
LUN's are made up of RAID groups, (Arrays in Promise WebPAM Pro speak).
Someone please correct me if I am wrong, but I don't think RAID Arrays can be comprised of Disks spanning different chassis.
Since the Metadata LUN is actually a two disk RAID 1 Array, I don't believe it can span chassis.
* * *
But if you swap the Spare nearest Video 2 with the MD nearest Video 3, that may make for a pretty sweet setup.
But with no "Scratch" or "Audio" disk made up of leftovers, you would have to have a more displined user group to keep smaller files out of the Video Affinity so has not to negatively impact performance of the main Storage Pool. |
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abstractrude
Xsan Master
Joined: 13 Mar 2008
Posts: 860
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| Posted: Tue Jan 12, 2010 1:53 pm Post subject: |
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| you definitley don't want your metadata LUN split across 2 chassis. |
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lucasnap
Xsan Master
Joined: 05 Oct 2006
Posts: 107
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| Posted: Wed Feb 03, 2010 9:47 am Post subject: |
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OK, thanks.
After a closer look it turned out the client had 750G drives in the existing V-TRAK E (he thought it were 1TB disks). So the two V-TRAK J were of a totally different size anyway. I made two stripe groups: One of the rest of the 750G disks after I made the MTD LUN. And the other stripe group of 1TB disks went to be the 'fast' stripegroup.
Long live Affinities.
Lucas |
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