[Gluster-users] Why does this setup not survive a node crash?

Sat Apr 16 22:41:20 UTC 2011

Can someone from dev please help me understand if this is expected? I
would expect gluster to transparently fail in distributed replica? But
it looks like if you lose a node you end having high response time
which is determinental to performance when under high load and a
gluster server crashes.

On Wed, Mar 16, 2011 at 11:19 AM, Burnash, James <jburnash at knight.com> wrote:
> Yes - the "long" response time went to about 18 seconds from over a minute (at least).
>
> Whether or not this is generally a good idea is something I'll let the devs and the list respond to.
>
>
> James Burnash, Unix Engineering
>
> -----Original Message-----
> From: Mohit Anchlia [mailto:mohitanchlia at gmail.com]
> Sent: Wednesday, March 16, 2011 2:17 PM
> To: Burnash, James; gluster-users at gluster.org
> Subject: Re: [Gluster-users] Why does this setup not survive a node crash?
>
> Thanks for sharing! Did it make it any faster after changing
> network.ping-timeout to 10 secs?
>
> On Wed, Mar 16, 2011 at 11:07 AM, Burnash, James <jburnash at knight.com> wrote:
>> So - answering myself with the (apparent) solution. The configuration IS correct as shown - the problems were elsewhere.
>>
>> Primary cause for this seems to be performing the gluster native client mount on a virtual machine WITHOUT using the " -O --disable-direct-io-mode" parameter.
>>
>> So I was mounting like this:
>>
>>        mount -t glusterfs jc1letgfs5:/test-pfs-ro1 /test-pfs2
>>
>> When I should have been doing this:
>>
>>        mount -t glusterfs -O --disable-direct-io-mode jc1letgfs5:/test-pfs-ro1 /test-pfs2
>>
>> Secondly, I changed the volume parameter "network.ping-timeout" from its default of 43 to 10 seconds, in order to get faster recovery from a downed storage node:
>>
>>        gluster volume set pfs-rw1 network.ping-timeout 10
>>
>> This configuration now survives the loss of either node of the two storage server mirrors. There is a noticeable delay before commands on the mount point complete the first time a command is issued after one of the nodes have gone done - but then they return at the same speed as when all nodes were present.
>>
>> Thanks especially to all who helped, and Anush who helped me troubleshoot it from a different angle.
>>
>> James Burnash, Unix Engineering
>>
>> -----Original Message-----
>> From: gluster-users-bounces at gluster.org [mailto:gluster-users-bounces at gluster.org] On Behalf Of Burnash, James
>> Sent: Friday, March 11, 2011 11:31 AM
>> To: gluster-users at gluster.org
>> Subject: Re: [Gluster-users] Why does this setup not survive a node crash?
>>
>> Could anyone else please take a peek at this an sanity check my configuration. I'm quite frankly at a loss and tremendously under the gun ...
>>
>> Thanks in advance to any kind souls.
>>
>> James Burnash, Unix Engineering
>>
>> -----Original Message-----
>> From: gluster-users-bounces at gluster.org [mailto:gluster-users-bounces at gluster.org] On Behalf Of Burnash, James
>> Sent: Thursday, March 10, 2011 3:55 PM
>> To: gluster-users at gluster.org
>> Subject: [Gluster-users] Why does this setup not survive a node crash?
>>
>> Perhaps someone will see immediately, given the data below, why this configuration will not survive a crash of one node - it appears that any node crashed out of this set will cause gluster native clients to hang until the node comes back.
>>
>> Given (2) initial storage servers (CentOS 5.5, Gluster 3.1.1):
>>
>> Starting out by creating a Replicated-Distributed pair with this command:
>> gluster volume create test-pfs-ro1 replica 2 jc1letgfs5:/export/read-only/g01 jc1letgfs6:/export/read-only/g01 jc1letgfs5:/export/read-only/g02 jc1letgfs6:/export/read-only/g02
>>
>> Which ran fine (thought I did not attempt to crash 1 of the pair)
>>
>> And then adding (2) more servers, identically configured, with this command:
>> gluster volume add-brick test-pfs-ro1 jc1letgfs7:/export/read-only/g01 jc1letgfs8:/export/read-only/g01 jc1letgfs7:/export/read-only/g02 jc1letgfs8:/export/read-only/g02
>> Add Brick successful
>>
>> root at jc1letgfs5:~# gluster volume info
>>
>> Volume Name: test-pfs-ro1
>> Type: Distributed-Replicate
>> Status: Started
>> Number of Bricks: 4 x 2 = 8
>> Transport-type: tcp
>> Bricks:
>> Brick1: jc1letgfs5:/export/read-only/g01
>> Brick2: jc1letgfs6:/export/read-only/g01
>> Brick3: jc1letgfs5:/export/read-only/g02
>> Brick4: jc1letgfs6:/export/read-only/g02
>> Brick5: jc1letgfs7:/export/read-only/g01
>> Brick6: jc1letgfs8:/export/read-only/g01
>> Brick7: jc1letgfs7:/export/read-only/g02
>> Brick8: jc1letgfs8:/export/read-only/g02
>>
>> And this volfile info out of the log file /var/log/glusterfs/etc-glusterd-mount-test-pfs-ro1.log:
>>
>> [2011-03-10 14:38:26.310807] W [dict.c:1204:data_to_str] dict: @data=(nil)
>> Given volfile:
>> +------------------------------------------------------------------------------+
>>  1: volume test-pfs-ro1-client-0
>>  2:     type protocol/client
>>  3:     option remote-host jc1letgfs5
>>  4:     option remote-subvolume /export/read-only/g01
>>  5:     option transport-type tcp
>>  6: end-volume
>>  7:
>>  8: volume test-pfs-ro1-client-1
>>  9:     type protocol/client
>>  10:     option remote-host jc1letgfs6
>>  11:     option remote-subvolume /export/read-only/g01
>>  12:     option transport-type tcp
>>  13: end-volume
>>  14:
>>  15: volume test-pfs-ro1-client-2
>>  16:     type protocol/client
>>  17:     option remote-host jc1letgfs5
>>  18:     option remote-subvolume /export/read-only/g02
>>  19:     option transport-type tcp
>>  20: end-volume
>>  21:
>>  22: volume test-pfs-ro1-client-3
>>  23:     type protocol/client
>>  24:     option remote-host jc1letgfs6
>>  25:     option remote-subvolume /export/read-only/g02
>>  26:     option transport-type tcp
>>  27: end-volume
>>  28:
>>  29: volume test-pfs-ro1-client-4
>>  30:     type protocol/client
>>  31:     option remote-host jc1letgfs7
>>  32:     option remote-subvolume /export/read-only/g01
>>  33:     option transport-type tcp
>>  34: end-volume
>>  35:
>> 36: volume test-pfs-ro1-client-5
>>  37:     type protocol/client
>>  38:     option remote-host jc1letgfs8
>>  39:     option remote-subvolume /export/read-only/g01
>>  40:     option transport-type tcp
>>  41: end-volume
>>  42:
>>  43: volume test-pfs-ro1-client-6
>>  44:     type protocol/client
>>  45:     option remote-host jc1letgfs7
>>  46:     option remote-subvolume /export/read-only/g02
>>  47:     option transport-type tcp
>>  48: end-volume
>>  49:
>>  50: volume test-pfs-ro1-client-7
>>  51:     type protocol/client
>>  52:     option remote-host jc1letgfs8
>>  53:     option remote-subvolume /export/read-only/g02
>>  54:     option transport-type tcp
>>  55: end-volume
>>  56:
>>  57: volume test-pfs-ro1-replicate-0
>>  58:     type cluster/replicate
>>  59:     subvolumes test-pfs-ro1-client-0 test-pfs-ro1-client-1
>>  60: end-volume
>>  61:
>>  62: volume test-pfs-ro1-replicate-1
>>  63:     type cluster/replicate
>>  64:     subvolumes test-pfs-ro1-client-2 test-pfs-ro1-client-3
>>  65: end-volume
>>  66:
>>  67: volume test-pfs-ro1-replicate-2
>>  68:     type cluster/replicate
>>  69:     subvolumes test-pfs-ro1-client-4 test-pfs-ro1-client-5
>>  70: end-volume
>>  71:
>>  72: volume test-pfs-ro1-replicate-3
>>  73:     type cluster/replicate
>>  74:     subvolumes test-pfs-ro1-client-6 test-pfs-ro1-client-7
>>  75: end-volume
>>  76:
>>  77: volume test-pfs-ro1-dht
>>  78:     type cluster/distribute
>>  79:     subvolumes test-pfs-ro1-replicate-0 test-pfs-ro1-replicate-1 test-pfs-ro1-replicate-2 test-pfs-ro1-replicate-3
>>  80: end-volume
>>  81:
>>  82: volume test-pfs-ro1-write-behind
>>  83:     type performance/write-behind
>>  84:     subvolumes test-pfs-ro1-dht
>>  85: end-volume
>>  86:
>>  87: volume test-pfs-ro1-read-ahead
>>  88:     type performance/read-ahead
>>  89:     subvolumes test-pfs-ro1-write-behind
>>  90: end-volume
>>  91:
>>  92: volume test-pfs-ro1-io-cache
>>  93:     type performance/io-cache
>>  94:     subvolumes test-pfs-ro1-read-ahead
>>  95: end-volume
>>  96:
>>  97: volume test-pfs-ro1-quick-read
>>  98:     type performance/quick-read
>>  99:     subvolumes test-pfs-ro1-io-cache
>> 100: end-volume
>> 101:
>> 102: volume test-pfs-ro1-stat-prefetch
>> 103:     type performance/stat-prefetch
>> 104:     subvolumes test-pfs-ro1-quick-read
>> 105: end-volume
>> 106:
>> 107: volume test-pfs-ro1
>> 108:     type debug/io-stats
>> 109:     subvolumes test-pfs-ro1-stat-prefetch
>> 110: end-volume
>>
>> Any input would be greatly appreciated. I'm working beyond my deadline already, and I'm guessing that I'm not seeing the forest for the trees here.
>>
>> James Burnash, Unix Engineering
>>
>>
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