Linux-Block Archive on lore.kernel.org
 help / color / Atom feed
From: Hannes Reinecke <hare@suse.de>
To: Alibek Amaev <alibek.a@gmail.com>,
	linux-block@vger.kernel.org, linux-scsi@vger.kernel.org
Subject: Re: Block device naming
Date: Thu, 16 May 2019 14:33:23 +0200
Message-ID: <e81e675e-e084-197a-fc13-101985bde590@suse.de> (raw)
In-Reply-To: <CA+TYKz1o=uOn0m3tPGqmNZtw7mGdZ7_BGX0C0RH9f3wnFDpO6Q@mail.gmail.com>

On 5/16/19 2:26 PM, Alibek Amaev wrote:
> Hi!
> 
> I want to address the following problem:
> On the system with hot-attached new storage volume, such as FC-switch
> update configuration for connected FC-HBA on servers, linux kernel
> reorder block devices and change names of block devices. Becouse
> scsi-id, wwn-id and other is a symbol links to block device names than
> on change block device name change path to device.
> This causes the server to stop working.
> 
> For example, on server present ZFS pool with attached device by scsi-id
> # zpool status
>    pool: pool
>   state: ONLINE
>    scan: scrub repaired 0 in 1h39m with 0 errors on Sun Oct  8 02:03:34 2017
> config:
> 
>      NAME                                      STATE     READ WRITE CKSUM
>      pool                                      ONLINE       0     0     0
>        scsi-3600144f0c7a5bc61000058d3b96d001d  ONLINE       0     0     0
> 
> Before export new block device from storage to hba, scsi-id have next
> path to device:
> /dev/disk/by-id/scsi-3600144f0c7a5bc61000058d3b96d001d -> ../../sdd
> 
> When added new block device by FC-switch, FC-HBA kernel change block
> device names:
> /dev/disk/by-id/scsi-3600144f0c7a5bc61000058d3b96d001d -> ../../sdf
> 
> and ZFS can't access to device until reboot (partprobe, zpool online
> -e pool scsi-3600144f0c7a5bc61000058d3b96d001d - may help or may not
> help)
> 
Hmm. That really is curious; typically existing devices will not be 
reassigned. Especially not if they are in use by something.
And the FC layer is going into quite some lengths to prevent this from 
happening.
So this really looks more like an issue with how exactly this 'adding 
new block device' step was done.

> Is there any way to fix or change this behavior of the kernel?
> 
As I said, this typically does not happen.
It would need closer examination to figure out what really happened.

> It may be more reasonable to immediately assign an unique persistent
> identifier of device and linking other identifiers with it?
> 
Which is what we try ...

> Also I think this is not specific problem of ZFS. And can occur with other
> file system modules.Moreover, I had previously encountered a similar
> problem - NetAPP
> storage attached to servers by FC and export multiple LUN - suddenly
> decided to change the order of LUNs and Ext4 on servers is switch to
> readonly mode because driver detect changes of magic number in
> superblocks of partitions.
> 
Suddently changing the order of LUNs is _not_ what is supposed to 
happen. This really sounds more like an issue with NetApp.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke            Teamlead Storage & Networking
hare@suse.de                              +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: Felix Imendörffer, Mary Higgins, Sri Rasiah
HRB 21284 (AG Nürnberg)

  reply index

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-16 12:26 Alibek Amaev
2019-05-16 12:33 ` Hannes Reinecke [this message]
2019-05-16 13:49   ` Alibek Amaev
2019-05-16 14:07     ` Hannes Reinecke
2019-05-17 11:24       ` Alibek Amaev

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=e81e675e-e084-197a-fc13-101985bde590@suse.de \
    --to=hare@suse.de \
    --cc=alibek.a@gmail.com \
    --cc=linux-block@vger.kernel.org \
    --cc=linux-scsi@vger.kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-Block Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-block/0 linux-block/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-block linux-block/ https://lore.kernel.org/linux-block \
		linux-block@vger.kernel.org linux-block@archiver.kernel.org
	public-inbox-index linux-block


Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-block


AGPL code for this site: git clone https://public-inbox.org/ public-inbox