O tamanho do disco varia - MooseFs

Question

Eu tenho 4 chunkservers moosefs com 8 2.7 TB de armazenamento em cada um, eu os monto usando o mfsmount e depois exporto com o nfs. Recentemente notei alta iowait em meus chunkservers, em seguida, enormes gotas de tamanho de montagem, ver os gráficos.

    

Answer 1

A razão deste problema foi a RAM no servidor mfs, ele começou a usar 50% de swap, quando eu aumentei a RAM, tudo começou a funcionar como esperado, mas ainda existe alto iowait no servidor do chunk, acho que nós deve passar de jbod para algum tipo de invasão.

    

Answer 2

Sobre o JBOD O site moosefs.com diz o seguinte (em "Melhores práticas"): ( link )

JBOD and XFS for Chunkservers

We recommend to connect to Chunkserver(s) JBODs. Just format the drive as XFS and mount on e.g. /mnt/chunk01, /mnt/chunk02, ... and put these paths into /etc/mfs/mfschunkserver.cfg. That's all.

We recommend such configuration mainly because of two reasons:

MooseFS has a mechanism of checking if the hard disk is in a good condition or not. MooseFS can discover broken disks, replicate the data and mark such disks as damaged. The situation is different with RAID: MooseFS algorithms do not work with RAIDs, therefore corrupted RAID arrays may be falsely reported as healthy/ok.

The other aspect is time of replication. Let's assume you have goal set to 2 for the whole MooseFS instance. If one 2 TiB drive breaks, the replication (from another copy) will last about 40-60 minutes. If one big RAID (e.g. 36 TiB) becomes corrupted, replication can last even for 12-18 hours. Until the replication process is finished, some of your data is in danger, because you have only one valid copy. If another disk or RAID fails during that time, some of your data may be irrevocably lost. So the longer replication period puts your data in greater danger.