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<span style="font-size:12pt">> I am not sure about the discrepancy of 3T. Maybe that is due to some ZFS and/or Lustre overhead?</span></div>
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<div>Slop space?</div>
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<div> https://openzfs.github.io/openzfs-docs/Performance%20and%20Tuning/Module%20Parameters.html#spa-slop-shift</div>
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-Laura</div>
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<div id="divRplyFwdMsg" dir="ltr"><font style="font-size:11pt" face="Calibri, sans-serif" color="#000000"><b>Od:</b> lustre-discuss <lustre-discuss-bounces@lists.lustre.org> v imenu Mohr, Rick via lustre-discuss <lustre-discuss@lists.lustre.org><br>
<b>Poslano:</b> torek, 06. april 2021 16:34<br>
<b>Za:</b> Makia Minich <makia@systemfabricworks.com>; lustre-discuss@lists.lustre.org <lustre-discuss@lists.lustre.org><br>
<b>Zadeva:</b> Re: [lustre-discuss] [EXTERNAL] ZFS and OST Space Difference</font>
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<div class="PlainText">Makia,<br>
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The drive sizes are 7.6 TB which translates to about 6.9 TiB (which is the unit that zpool uses for "T"). So the zpool sizes as just 10 x 6.9T = 69T since zpool shows the total amount of disk space available to the pool. The usable space (which is what df
is reporting) should be more like 0.8 x 69T = 55T. I am not sure about the discrepancy of 3T. Maybe that is due to some ZFS and/or Lustre overhead?<br>
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--Rick<br>
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\ufeffOn 4/6/21, 3:49 PM, "lustre-discuss on behalf of Makia Minich" <lustre-discuss-bounces@lists.lustre.org on behalf of makia@systemfabricworks.com> wrote:<br>
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I believe this was discussed a while ago, but I was unable to find clear answers, so I\u2019ll re-ask in hopefully a slightly different way.<br>
On an OST, I have 30 drives, each at 7.6TB. I create 3 raidz2 zpools of 10 devices (ashift=12):<br>
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[root@lustre47b ~]# zpool list<br>
NAME SIZE ALLOC FREE CKPOINT EXPANDSZ FRAG CAP DEDUP HEALTH ALTROOT<br>
oss55-0 69.9T 37.3M 69.9T - - 0% 0% 1.00x ONLINE -<br>
oss55-1 69.9T 37.3M 69.9T - - 0% 0% 1.00x ONLINE -<br>
oss55-2 69.9T 37.4M 69.9T - - 0% 0% 1.00x ONLINE -<br>
[root@lustre47b ~]#<br>
<br>
<br>
Running a mkfs.lustre against these (and the lustre mount) and I see:<br>
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[root@lustre47b ~]# df -h | grep ost<br>
oss55-0/ost165 52T 27M 52T 1% /lustre/ost165<br>
oss55-1/ost166 52T 27M 52T 1% /lustre/ost166<br>
oss55-2/ost167 52T 27M 52T 1% /lustre/ost167<br>
[root@lustre47b ~]#<br>
<br>
<br>
Basically, we\u2019re seeing a pretty dramatic loss in capacity (156TB vs 209.7TB, so a loss of about 50TB). Is there any insight on where this capacity is disappearing to? If there some mkfs.lustre or zpool option I missed in creating this? Is something just
reporting slightly off and that space really is there?<br>
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Thanks.<br>
<br>
\u2014<br>
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Makia Minich<br>
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Chief Architect<br>
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System Fabric Works<br>
"Fabric Computing that Works\u201d<br>
<br>
"Oh, I don't know. I think everything is just as it should be, y'know?\u201d<br>
- Frank Fairfield<br>
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