From: Wang Yugui <wangyugui@e16-tech.com>
To: cluster-devel.redhat.com
Subject: [Cluster-devel] question about gfs2 multiple device support
Date: Tue, 09 May 2023 06:25:46 +0800 [thread overview]
Message-ID: <20230509062545.D02E.409509F4@e16-tech.com> (raw)
In-Reply-To: <20230424193510.4A1D.409509F4@e16-tech.com>
Hi,
> Hi,
>
> > Hi,
> >
> > On Sat, 2023-04-22 at 09:20 +0800, Wang Yugui wrote:
> > > Hi,
> > >
> > > Is there some work for gfs2 multiple device support?
> > >
> > Do you mean multiple devices generically, or specifically the md
> > driver?
> >
> > > if multiple device support,
> > > 1, No need of RAID 0/1/5/6 support.
> > > ?? nvme SSD is fast enough for single thread write.
> > I'm not sure I understand this. Multiple device support generally means
> > at least one of the RAID modes.
>
> we can support linear mode (same as lvcreate --type linear) only firstly.
>
> > > 2, can we limit one journal into one device?
> > The filesystem always assumes a single device with one or more
> > journals. If multiple devices are used, that is done at the block
> > layer, which is below the filesystem layer.
> >
> > >
> > > 3, can we just write lock one device, so better write throughput?
> > Do you have a specific application in mind? Or certain performance
> > levels that you need to hit? The write performance will depend a lot on
> > the I/O pattern, and the underlying device performance. We'll need a
> > bit more detail to be more specific I'm afraid,
>
> gfs2 use 'SCSI PERSISTENT RESERVE' or similar method to lock block device
> when multiple hosts access the gfs2 at the same time?
It seems that lock_dlm does NOT use 'SCSI PERSISTENT RESERVE' or similar method
to lock block device.
it lock in the unit of 'resource group'.
Best Regards
Wang Yugui (wangyugui at e16-tech.com)
2023/05/09
> if gfs2 use multiple device directly rather than through lvm, then we
> can just lock one device rather than all device?
> - journal lock one device only
> - data write lock one device only.
>
> Now SSD/SAN is very fast and become cheaper, and we can use multiple
> SSD/SAN for one bigger filesystem and bigger HPC cluster?
>
> Best Regards
> Wang Yugui (wangyugui at e16-tech.com)
> 2023/04/24
prev parent reply other threads:[~2023-05-08 22:25 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-04-22 1:20 [Cluster-devel] question about gfs2 multiple device support Wang Yugui
2023-04-24 10:00 ` Steven Whitehouse
2023-04-24 11:35 ` Wang Yugui
2023-05-08 22:25 ` Wang Yugui [this message]
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