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Adding DAE and 15 x 2TB NL-SAS disks to existing FAST pool
I have an existing VNX 5300 with a mix of SSD, SAS, and NL-SAS all in a 60TB (raw) FAST pool. I set it up in late 2011 with all drives in the pool being in 5-drive RAID5 sets. I am nearing capacity and so we've purchased and installed an additional DAE with 15 x 2TB NL-SAS drives.
When we originally bought the VNX, I was told one of the only downsides to using the FAST pools was that in the future, when I wanted to add more storage I would need to add a mix of all drive types again, if I wanted to retain the same performance. Apparently adding just NL-SAS later would not really be truly added into the pool and data that lived on it would not be balanced with the original pool (or something like that). But then sometime last year an EMC reseller told me this had been remedied and that with the newer FLARE you could simply add and expand with NL-SAS and it would re-balance the existing pool. Of course with the caveat that we are assuming you really only need additional capacity storage and not performance storage, which is exactly what we need right now.
I have had several FLARE upgrades since we purchased the VNX 5300, but in searching the forum here, I am getting the impression you need 5.32 for this rebalancing feature, and I am on 5.31.000.5.720. So I have a few questions:
1) If that is true that I need 5.32, do I need to get the FLARE upgraded done BEFORE I try and expand the pool with these new disks?
2) The local SE that showed up to connect/cable my new DAE (didn't even know EMC was sending someone out) said he did not recommend going to "the latest FLARE" because he had seen quite a few problems with thin provisioning and FAST causing crashes. He didn't give me a version number and at the time I had not even started reading online as to which FLARE could do what. Is the latest 5.32? And if so, have those issues he mentioned been fixed? I do have a few thin provisioned LUNs.
thanks,
Ben
dynamox
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February 28th, 2013 06:00
NL-SAS is your lowest tier right, when you add more NL-SAS drives ..it will take the existing 1g chunks from that tier and spread then evenly onto the new NL-SAS drives, giving you nice and even spread. Before it would start allocating new slices on the new drives until their utilization would equal utilization of the old drives.
Rainer_EMC
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February 28th, 2013 06:00
With 5.32 it will re-balance within the tier every time FAST VP tiering is running
If you don’t have FAST VP enabled – then you should first upgrade to 5.32 before adding this since then the re-balancing will only run once when you add the disks
Rainer_EMC
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February 28th, 2013 06:00
Between the tiers – moving 1GB slice up and down from EFD, SAS and NL-SAS
Within a tier – moving 1 GB slices within all the space of a tier like SAS so that its re-balancing within a tier
dynamox
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February 28th, 2013 06:00
haha ..not sure how to take it ..but i'll take it as a compliment
r1214
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February 28th, 2013 06:00
Can you elaborate on (1)? Not sure I understand what you mean by rebalance between the tiers versus rebalancing within the same tier
RRR
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February 28th, 2013 06:00
Another PRO of 32 is that you can now have RAID10, RAID5 and RAID6 in the same pool, each containing different numbers of disks in the private RAID Groups. For the rest: listen to D, he does make sense sometimes
dynamox
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February 28th, 2013 06:00
1) yes, you want it to rebalance between the tiers but also with 32 it will rebalance within the same tier.
2) i have been running 32 since last December, no issues to report.
r1214
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February 28th, 2013 07:00
You guys are awesome, thanks for the replies!
When you all say FAST VP, you mean the auto tiering that runs each night? If so, yes, I have that enabled and running starting at 9pm each night.
So just to clarify and summarize- basically with my current 5.31 version, I can go ahead and expand and get the benefit of existing data in my SAS and SSD tiers being able to move down into the new 15 NL-SAS drives nightly with FAST-VP, BUT, any data that is already within my old NL-SAS tier will not get redistributed to the new NL-SAS drives? And if that's the case, how does FAST-VP decide which set of NL-SAS drives (old or new) to move data down to when it's neccessary?
Otherwise, I can upgrade to 5.32, now or later, and then it will act as though the new NL-SAS drives were there all along and distribute more evenly between the different sets of NL-SAS?
dynamox
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February 28th, 2013 07:00
they way it was explained to me was that FAST will start using the new NL-SAS drives, new LUNs will be created on the new drives as well but existing data will not get re-distributed all at once like it does when you are running 32 and add brand new drives.
since you are licensed for FAST you are right, as soon as you upgrade to 32 it will start balancing within the NL-SAS tier. What i don't know if it's going to be one big rebalance job to "equalize" everything based on utilization or gradual movement based on performance.
RRR
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February 28th, 2013 07:00
Please do
r1214
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February 28th, 2013 09:00
Thank you sir. Sounds like I just need to go ahead and get 5.32 installed.
Anyone know about these issues the local EMC SE was talking about in regards to thin provisioning and crashes with FAST within 5.32?
kelleg
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March 1st, 2013 13:00
In R32, when you first expand a Pool, the re-balancing will start automatically and run to completion. With very large Pools, this may take some time. If you add NL-SAS, it will reblanace the data over all the disks in that tier - old and new. Same if you add more SAS drives. Once all the re-balancing has finished, then each night when auto-tiering runs, it will balance between tires and within tiers - it's an ongoing process.
As to problems with thin provisioning can crashes, we've seem some issues as is normal with a new release that adds a lot of new featues (VNX Snapshots, Horizontal tiering, mixed raid types within a single Pool, Thick LUN slice allocation, etc). The current patch level is .201 and there are a number of fixes within that release. You can get the release notes for this version on the support.emc.com site under the VNX section and Documents/Release Notes - all are dated Feb. 22, 2013. The release notes for Unisphere and Block also list all the new features.
docu45743_VNX-Operating-Environment-for-Block-Release-Notes-Version-05.32.000.5.201.pdf
docu45745_Unisphere-Release-Notes-Version-1.2.25.1.0156.pdf
glen
GearoidG
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March 1st, 2013 13:00
Yup SMLink is ran due to ETA emc308955 where pool luns can go offline,
Out of curiosity did you ever receive an alert about this ETA?
Cheers
Gearoid
r1214
38 Posts
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March 1st, 2013 13:00
Thanks Glen! We are going to do the upgrade this Wednesday. The local SE had me run a utility called SMLink_Check to make sure there were no issues with existing thin luns (and apparently thick too) and FAST VP. The check came back clean so we're going to update.
r1214
38 Posts
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March 7th, 2013 07:00
Yes I believe I did get an ETA on it. I'd have to go back and look through my emails to be certain, but I'm pretty sure I did.
We completed the 5.32 upgrade yesterday and I just expanded my storage pool a few minutes ago. It is rebalancing as I type this. It's nice to sigh a breath of relief now that I have a bunch of extra space to work with