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| New Virtual Volume Max size frustration https://3parug.net/viewtopic.php?f=18&t=3090 |
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| Author: | mfahey [ Mon Feb 04, 2019 11:49 am ] |
| Post subject: | New Virtual Volume Max size frustration |
I recently added 24 1.2TB FC Drives with an enclosure. I want to create a virtual volume using all the space. The CPG says Estimated maximum CPG size 19,248 GiB My question is what is the largest I should create the virtual volume ? HPE Claimed I can get 21.5 TB usable space. Do I need to leave 10% free when I create the virtual volume? When I initially created it I got warnings saying it was at 100% used space. Thanks. |
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| Author: | MammaGutt [ Tue Feb 05, 2019 12:29 am ] |
| Post subject: | Re: New Virtual Volume Max size frustration |
With 3PAR OS 3.3.1 you can create thin volumes up to 64 TB, with dedupe and/or compression or earlier versions of 3PAR OS, the max is 16TB. |
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| Author: | mfahey [ Tue Feb 05, 2019 3:39 pm ] |
| Post subject: | Re: New Virtual Volume Max size frustration |
I understand what the Max limits are. That wasn't the question. The question was If I create a virtual volume 100% of the available space I get critical warnings. My question was is it best practice to create a virtual volume no more then 90% of the available space? |
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| Author: | MammaGutt [ Tue Feb 05, 2019 4:21 pm ] |
| Post subject: | Re: New Virtual Volume Max size frustration |
Well, that is a question which raises more. Will you use replication? (If so there will be snapshots) Do you plan to use snapshots in general?(multiple external applications can/may/will use snapshots) What type of volumes will you use? What sparring level are you using and what is the hardware config?(nodes, cages,drives) How many drives can you accept failing before replacing and rebuilding? (naturally simulatious failures are decided by RAID level) Answer «correct» on all of these and you can safely use ~100%, answer «wrong» and it could be way less. The only Best Practice (which is the general advise for the general use case) is always ensure you add more drives before you go full. |
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| Author: | nicDM77 [ Wed Feb 06, 2019 8:20 am ] |
| Post subject: | Re: New Virtual Volume Max size frustration |
I'm also curious why you would want to create such a huge LUN. It implies having a single disk queue, which can quickly result in degraded performance, both ingress & egress. Especially on spinning media. Depending on the use case I would consider splitting the CPG in 'acceptable' LUN sizes and trust your multipathing to properly handle your queues. |
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| Author: | Richard Siemers [ Tue Feb 12, 2019 10:25 pm ] |
| Post subject: | Re: New Virtual Volume Max size frustration |
Assuming your not doing thin provisioning, dedupe/compress, and therefore won't run out of space... 3PAR can fully provision 100% of the usable space without taking a performance hit like some modern arrays, software defined storage clusters, that need 10% - 20% free space to run optimal. |
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