topic Re: Aggregate performance issue after adding disks in ONTAP Discussions

Aggregate performance issue after adding disks

mkopenski — Thu, 05 Jun 2025 07:24:22 GMT

After adding 4 disks to an aggregate one of them is at a constant 100% utilization, currently running a reallocate.

The question is why is only that one disk at 100% while the other ones that were added ~25% along with the rest of the disks in the raid group?

Current status of the aggregate is redirect, which is expected I guess.

Any suggestions?

Re: Aggregate performance issue after adding disks

mkopenski — Tue, 01 Sep 2009 16:08:51 GMT

Here are the stats of that aggregate from statit - 1b.89 is at 100 , 1b.88 2c.29 and 2b.59 were the other disks that were added

/aggr1/plex0/rg0:
4c.60              4 11.76    0.33   1.00 9722   5.44 26.41   243   5.99   8.93   451   0.00   ....     .   0.00   ....     .
4c.61              4 12.08    0.33   1.00 22556   5.81 24.85   220   5.94   8.68   486   0.00   ....     .   0.00   ....     .
4c.45             26 55.48   44.41   2.92 5229   4.01 13.32 1123   7.07   9.08 1141   0.00   ....     .   0.00   ....     .
4c.49             22 50.59   39.62   2.97 4436   3.51 13.93   931   7.46   9.40   848   0.00   ....     .   0.00   ....     .
4c.50             24 54.13   43.24   2.93 4607   3.49 14.91   872   7.40   9.33 1164   0.00   ....     .   0.00   ....     .
2c.51             24 53.83   42.98   2.87 4695   3.32 13.49   812   7.53 10.01   996   0.00   ....     .   0.00   ....     .
4c.52             24 55.43   44.26   2.73 5159   3.49 13.96   859   7.68   9.03   990   0.00   ....     .   0.00   ....     .
4c.53             24 53.39   42.22   3.01 4516   3.60 14.21   911   7.57   9.28 1014   0.00   ....     .   0.00   ....     .
4c.54             23 50.81   39.66   2.93 4677   3.58 13.87   947   7.57   9.73   993   0.00   ....     .   0.00   ....     .
2c.55             23 52.12   41.37   3.04 4380   3.43 13.41   885   7.33   9.89 1066   0.00   ....     .   0.00   ....     .
2c.56             24 54.28   43.05   2.97 4684   3.97 14.16   917   7.25   9.33   944   0.00   ....     .   0.00   ....     .
4c.57             25 56.02   44.82   2.96 4536   3.75 13.78   959   7.46   9.40   974   0.00   ....     .   0.00   ....     .
2c.58             23 52.35   41.92   2.89 4758   3.30 13.37   929   7.12 10.37   906   0.00   ....     .   0.00   ....     .
2c.59             25 55.65   44.45   3.10 4551   3.73 15.05   925   7.48   8.68 1190   0.00   ....     .   0.00   ....     .
2c.48             23 50.90   40.10   2.51 5662   3.71 16.82   683   7.09   8.96 1147   0.00   ....     .   0.00   ....     .
2b.87             23 48.75   38.95   2.17 6092   4.34 28.68   338   5.45   8.01   561   0.00   ....     .   0.00   ....     .
2b.59             21 47.78   38.14   2.10 5910   4.60 29.73   368   5.05   9.32   721   0.00   ....     .   0.00   ....     .
2c.29             22 47.01   37.34   2.22 5791   4.64 29.49   384   5.03   9.47 1143   0.00   ....     .   0.00   ....     .
1b.88             22 47.84   38.23   2.09 6850   4.56 29.97   296   5.05   9.27   495   0.00   ....     .   0.00   ....     .
1b.89            100 47.17   37.53   1.93 79596   4.60 29.81 5836   5.05   9.14 23635   0.00   ....     .   0.00   ....     .

Re: Aggregate performance issue after adding disks

cedric_renauld — Tue, 01 Sep 2009 18:38:17 GMT

Hi Mark

So the 1b.89 disk ins't the Parity drive ?

Cf with sysconfig -r ... Maybee

Re: Aggregate performance issue after adding disks

mkopenski — Tue, 01 Sep 2009 18:41:23 GMT

It is a data disk, none of the other disks are showing any issues like

this

data 1b.89 1b 5 9 FC:B - FCAL 15000

272000/557056000 280104/573653840

Re: Aggregate performance issue after adding disks

mkopenski — Tue, 01 Sep 2009 22:07:12 GMT

Support had me fail a disk, which leveled the io across the raid group

Re: Aggregate performance issue after adding disks

amiller_1 — Wed, 02 Sep 2009 13:23:37 GMT

That's definitely one approach -- if happens in the future I'd look at the reallocate command as well (at the physical level).

Re: Aggregate performance issue after adding disks

mkopenski — Wed, 02 Sep 2009 17:56:58 GMT

Did start a reallocate after adding the disks, was going very slow

The suggestion to prevent this in the future was - simplified

1. Try to free up space in aggregate <90% and clean up snapshots - This one was at 91.3%

2. Run reallocate before adding disks.

3. Add less disks at a time

4. Run reallocate after adding disks

Re: Aggregate performance issue after adding disks

amiller_1 — Tue, 15 Sep 2009 03:33:11 GMT

Very helpful to know what worked in real life....thanks for posting back.