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Posted to user@cassandra.apache.org by Loïc CHANEL via user <us...@cassandra.apache.org> on 2023/01/06 09:28:11 UTC
Re: Cassandra uneven data repartition
Hi team,
Does anyone know how to even the data between several data disks ?
Another approach could be to prevent Cassandra from writing on a 90% full
disk, but is there a way to do that ?
Thanks,
Loïc CHANEL
System Big Data engineer
SoftAtHome (Lyon, France)
Le lun. 19 déc. 2022 à 11:07, Loïc CHANEL <lo...@telecomnancy.net> a
écrit :
> Hi team,
>
> I had a disk space issue on a Cassandra server, and I noticed that the
> data was not evenly shared between my 15 disks.
> Here is the repartition :
> /dev/vde1 99G 89G 4.7G *96%* /volumes/cassandra/data/data1
> /dev/vdd1 99G 51G 44G 54% /volumes/cassandra/data/data2
> /dev/vdf1 99G 57G 38G 61% /volumes/cassandra/data/data3
> /dev/vdg1 99G 51G 44G 54% /volumes/cassandra/data/data4
> /dev/vdh1 99G 50G 44G 54% /volumes/cassandra/data/data5
> /dev/vdi1 99G 50G 44G 53% /volumes/cassandra/data/data6
> /dev/vdj1 99G 77G 17G 83% /volumes/cassandra/data/data7
> /dev/vdk1 99G 49G 45G 53% /volumes/cassandra/data/data8
> /dev/vdl1 99G 52G 42G 56% /volumes/cassandra/data/data9
> /dev/vdm1 99G 50G 45G 53% /volumes/cassandra/data/data10
> /dev/vdn1 99G 47G 47G *51%* /volumes/cassandra/data/data11
> /dev/vdo1 99G 50G 44G 54% /volumes/cassandra/data/data12
> /dev/vdp1 99G 52G 43G 55% /volumes/cassandra/data/data13
> /dev/vdq1 99G 49G 45G 52% /volumes/cassandra/data/data14
> /dev/vdr1 99G 50G 44G 53% /volumes/cassandra/data/data15
>
> Do you know what could cause this, and how to even a little bit the data
> between the disks to avoid any disk saturation situation ? Because I
> noticed that when approaching 5% disk space on one disk, Cassandra
> performance drops.
> Thanks,
>
>
> Loïc CHANEL
> System Big Data engineer
> SoftAtHome (Lyon, France)
>
Fwd: Re: Cassandra uneven data repartition
Posted by onmstester onmstester via user <us...@cassandra.apache.org>.
Isn't there a very big (>40GB) sstable in /volumes/cassandra/data/data1? If there is you could split it or change your data model to prevent such sstables.
Sent using https://www.zoho.com/mail/
============ Forwarded message ============
From: Loïc CHANEL via user <us...@cassandra.apache.org>
To: <us...@cassandra.apache.org>
Date: Fri, 06 Jan 2023 12:58:11 +0330
Subject: Re: Cassandra uneven data repartition
============ Forwarded message ============
Hi team,
Does anyone know how to even the data between several data disks ?
Another approach could be to prevent Cassandra from writing on a 90% full disk, but is there a way to do that ?
Thanks,
Loïc CHANEL
System Big Data engineer
SoftAtHome (Lyon, France)
Le lun. 19 déc. 2022 à 11:07, Loïc CHANEL <ma...@telecomnancy.net> a écrit :
Hi team,
I had a disk space issue on a Cassandra server, and I noticed that the data was not evenly shared between my 15 disks.
Here is the repartition :
/dev/vde1 99G 89G 4.7G 96% /volumes/cassandra/data/data1
/dev/vdd1 99G 51G 44G 54% /volumes/cassandra/data/data2
/dev/vdf1 99G 57G 38G 61% /volumes/cassandra/data/data3
/dev/vdg1 99G 51G 44G 54% /volumes/cassandra/data/data4
/dev/vdh1 99G 50G 44G 54% /volumes/cassandra/data/data5
/dev/vdi1 99G 50G 44G 53% /volumes/cassandra/data/data6
/dev/vdj1 99G 77G 17G 83% /volumes/cassandra/data/data7
/dev/vdk1 99G 49G 45G 53% /volumes/cassandra/data/data8
/dev/vdl1 99G 52G 42G 56% /volumes/cassandra/data/data9
/dev/vdm1 99G 50G 45G 53% /volumes/cassandra/data/data10
/dev/vdn1 99G 47G 47G 51% /volumes/cassandra/data/data11
/dev/vdo1 99G 50G 44G 54% /volumes/cassandra/data/data12
/dev/vdp1 99G 52G 43G 55% /volumes/cassandra/data/data13
/dev/vdq1 99G 49G 45G 52% /volumes/cassandra/data/data14
/dev/vdr1 99G 50G 44G 53% /volumes/cassandra/data/data15
Do you know what could cause this, and how to even a little bit the data between the disks to avoid any disk saturation situation ? Because I noticed that when approaching 5% disk space on one disk, Cassandra performance drops.
Thanks,
Loïc CHANEL
System Big Data engineer
SoftAtHome (Lyon, France)