Re: [zfs-discuss] questions about ZFS Send/Receive

[Ross]

Just checking, are you planning to have the receiving ZFS system read only?  
I'm not sure how ZFS receive works on a system if changes have been made, but I 
would expect they would be overwritten.
 
 
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Re: [zfs-discuss] questions about ZFS Send/Receive

[Justin Vassallo]

>It depends: if you like to be able to restore single files, zfs send/recv
would 
>not be apropriate.

Why not?

With zfs you can easily view any file/dir from a snapshot (via the .zfs
dir). You can also copy that instance of the file into your running fs with
cp.

justin


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Re: [zfs-discuss] questions about ZFS Send/Receive

[Joerg Schilling]

eric kustarz <[EMAIL PROTECTED]> wrote:

> > Best Backup Script That Doesn't Do Backups, but I can't find it. In  
> > essence, it just created a list of what changed since the last  
> > backup and allowed you to use tar/cpio/cp - whatever to do the backup.
>
> I think zfs send/recv would be a great way to go here - see below.

It depends: if you like to be able to restore single files, zfs send/recv would 
not be apropriate.

Jörg

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Re: [zfs-discuss] questions about ZFS Send/Receive

[Joerg Schilling]

"Chris Cosby" <[EMAIL PROTECTED]> wrote:

> If they are truly limited, something like an rsync or similar. There was a
> script being thrown around a while back that was touted as the Best Backup
> Script That Doesn't Do Backups, but I can't find it. In essence, it just
> created a list of what changed since the last backup and allowed you to use
> tar/cpio/cp - whatever to do the backup.

star can do real "incremental" backups using a built-in support for changed 
files
that works the same way as ufsdump does.

As a result, star also allows to do incremental restores from these archives
which is something other star implementations do not offer in a working way.

There is also the pax implementaion from David Korn and Glenn Fowler that does
"differential" backups, but I did not yet test this.

Jörg

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Re: [zfs-discuss] questions about ZFS Send/Receive

[Chris Cosby]

Obviously, I should stop answering, as all I deal with and all that I will
deal with is GA Solaris. OpenSolaris might as well not exist as far as I'm
concerned. With that in mind, I'll just keep reading and appreciating all of
the good zfs info that comes along.

Peace out.

On Tue, Jul 29, 2008 at 5:54 PM, eric kustarz <[EMAIL PROTECTED]> wrote:

>
> On Jul 29, 2008, at 2:24 PM, Chris Cosby wrote:
>
>
>>
>> On Tue, Jul 29, 2008 at 5:13 PM, Stefano Pini <[EMAIL PROTECTED]>
>> wrote:
>> Hi guys,
>> we are  proposing  a customer  a couple of X4500 (24 Tb) used as NAS (i.e.
>> NFS server).
>> Both server will contain the same files and should be accessed by
>> different clients at the same time (i.e. they should be both active)
>> So we need to guarantee that both x4500 contain the same files:
>> We could simply copy the contents on both x4500 , which is an option
>> because the "new files" are in a limited number and rate , but we would
>> really like to use ZFS send & receive commands:
>> If they are truly limited, something like an rsync or similar. There was a
>> script being thrown around a while back that was touted as the Best Backup
>> Script That Doesn't Do Backups, but I can't find it. In essence, it just
>> created a list of what changed since the last backup and allowed you to use
>> tar/cpio/cp - whatever to do the backup.
>>
>
> I think zfs send/recv would be a great way to go here - see below.
>
>
>>
>>
>>
>> AFAIK the commands works fine but  generally speaking are there any known
>> limitations ?
>> And, in detail , it is not clear  if the receiving ZFS file system could
>> be used regularly while it is in "receiving mode":
>> in poor words is it possible to read and export in nfs,   files from a
>>  ZFS file system while it is receiving update from  another  ZFS send ?
>> First, the zfs send works only on a snapshot. -i sends incremental
>> snapshots, so you would think that would work. From the zfs man page, you'll
>> see that during a receive, the destination file system is unmounted and
>> cannot be accessed during the receive.
>>
>>  If an incremental stream is received, then the  destina-
>> tion file system must already exist, and its most recent
>> snapshot must match the incremental stream's source. The
>> destination  file  system and all of its child file sys-
>> tems are unmounted and cannot  be  accessed  during  the
>> receive operation.
>>
>
> Actually we don't unmount the file systems anymore for incremental
> send/recv, see:
> 6425096 want online 'zfs recv' (read only and read/write)
>
> Available since November 2007 in OpenSolaris/Nevada.  Coming to a s10u6
> near you.
>
> eric
>



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Re: [zfs-discuss] questions about ZFS Send/Receive

[eric kustarz]

On Jul 29, 2008, at 2:24 PM, Chris Cosby wrote:

>
>
> On Tue, Jul 29, 2008 at 5:13 PM, Stefano Pini <[EMAIL PROTECTED]>  
> wrote:
> Hi guys,
> we are  proposing  a customer  a couple of X4500 (24 Tb) used as NAS  
> (i.e. NFS server).
> Both server will contain the same files and should be accessed by  
> different clients at the same time (i.e. they should be both active)
> So we need to guarantee that both x4500 contain the same files:
> We could simply copy the contents on both x4500 , which is an option  
> because the "new files" are in a limited number and rate , but we  
> would really like to use ZFS send & receive commands:
> If they are truly limited, something like an rsync or similar. There  
> was a script being thrown around a while back that was touted as the  
> Best Backup Script That Doesn't Do Backups, but I can't find it. In  
> essence, it just created a list of what changed since the last  
> backup and allowed you to use tar/cpio/cp - whatever to do the backup.

I think zfs send/recv would be a great way to go here - see below.

>
>
>
>
> AFAIK the commands works fine but  generally speaking are there any  
> known limitations ?
> And, in detail , it is not clear  if the receiving ZFS file system  
> could be used regularly while it is in "receiving mode":
> in poor words is it possible to read and export in nfs,   files from  
> a  ZFS file system while it is receiving update from  another  ZFS  
> send ?
> First, the zfs send works only on a snapshot. -i sends incremental  
> snapshots, so you would think that would work. From the zfs man  
> page, you'll see that during a receive, the destination file system  
> is unmounted and cannot be accessed during the receive.
>
>   If an incremental stream is received, then the  destina-
>  tion file system must already exist, and its most recent
>  snapshot must match the incremental stream's source. The
>  destination  file  system and all of its child file sys-
>  tems are unmounted and cannot  be  accessed  during  the
>  receive operation.

Actually we don't unmount the file systems anymore for incremental  
send/recv, see:
6425096 want online 'zfs recv' (read only and read/write)

Available since November 2007 in OpenSolaris/Nevada.  Coming to a  
s10u6 near you.

eric
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Re: [zfs-discuss] questions about ZFS Send/Receive

[Richard Elling]

Stefano Pini wrote:
> Hi guys,
> we are  proposing  a customer  a couple of X4500 (24 Tb) used as NAS 
> (i.e. NFS server).
> Both server will contain the same files and should be accessed by 
> different clients at the same time (i.e. they should be both active)

What exactly are they trying to do?

AVS can be used to keep two systems in sync, but for a simple design,
there should be two NFS file systems, one active for each X4500.
There has recently been some discussions on
[EMAIL PROTECTED]
about using AVS to keep the unshared storage in sync.
 -- richard

> So we need to guarantee that both x4500 contain the same files:
> We could simply copy the contents on both x4500 , which is an option 
> because the "new files" are in a limited number and rate , but we 
> would really like to use ZFS send & receive commands:
>
> AFAIK the commands works fine but  generally speaking are there any 
> known limitations ?
> And, in detail , it is not clear  if the receiving ZFS file system 
> could be used regularly while it is in "receiving mode":
> in poor words is it possible to read and export in nfs,   files from 
> a  ZFS file system while it is receiving update from  another  ZFS send ?
>
> Clearly  until the new updates are received and applied the old copy 
> would be used
>
> TIA
> Stefano
>
>
>
> Sun Microsystems Spa
> Viale Fulvio testi 327
> 20162 Milano ITALY
> me *STEFANO PINI*
> Senior Technical Specialist at Sun Microsystems Italy 
> 
> contact | [EMAIL PROTECTED]  | +39 02 
> 64152150
>
>
> 
>
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Re: [zfs-discuss] questions about ZFS Send/Receive

[Chris Cosby]

On Tue, Jul 29, 2008 at 5:13 PM, Stefano Pini <[EMAIL PROTECTED]> wrote:

> Hi guys,
> we are  proposing  a customer  a couple of X4500 (24 Tb) used as NAS (i.e.
> NFS server).
> Both server will contain the same files and should be accessed by different
> clients at the same time (i.e. they should be both active)
> So we need to guarantee that both x4500 contain the same files:
> We could simply copy the contents on both x4500 , which is an option
> because the "new files" are in a limited number and rate , but we would
> really like to use ZFS send & receive commands:

If they are truly limited, something like an rsync or similar. There was a
script being thrown around a while back that was touted as the Best Backup
Script That Doesn't Do Backups, but I can't find it. In essence, it just
created a list of what changed since the last backup and allowed you to use
tar/cpio/cp - whatever to do the backup.


>
>
> AFAIK the commands works fine but  generally speaking are there any known
> limitations ?
> And, in detail , it is not clear  if the receiving ZFS file system could be
> used regularly while it is in "receiving mode":
> in poor words is it possible to read and export in nfs,   files from a  ZFS
> file system while it is receiving update from  another  ZFS send ?

First, the zfs send works only on a snapshot. -i sends incremental
snapshots, so you would think that would work. From the zfs man page, you'll
see that during a receive, the destination file system is unmounted and
cannot be accessed during the receive.

  If an incremental stream is received, then the  destina-
 tion file system must already exist, and its most recent
 snapshot must match the incremental stream's source. The
 destination  file  system and all of its child file sys-
 tems are unmounted and cannot  be  accessed  during  the
 receive operation.


>
> Clearly  until the new updates are received and applied the old copy would
> be used
>
> TIA
> Stefano
>
>
>
> Sun Microsystems Spa
> Viale Fulvio testi 327
> 20162 Milano ITALY
> me *STEFANO PINI*
> Senior Technical Specialist at Sun Microsystems Italy <
> http://www.sun.com/italy>
> contact | [EMAIL PROTECTED]  | +39 02
> 64152150
>
>
>
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Re: [zfs-discuss] questions about ZFS Send/Receive

[Richard Elling]

Stefano Pini wrote:
> Hi guys,
> we are  proposing  a customer  a couple of X4500 (24 Tb) used as NAS 
> (i.e. NFS server).
> Both server will contain the same files and should be accessed by 
> different clients at the same time (i.e. they should be both active)
> So we need to guarantee that both x4500 contain the same files:
> We could simply copy the contents on both x4500 , which is an option 
> because the "new files" are in a limited number and rate , but we 
> would really like to use ZFS send & receive commands:
>
> AFAIK the commands works fine but  generally speaking are there any 
> known limitations ?

zfs send/receive work on snapshots, not live data.
AVS can replicate ZFS live data, but works in an active/passive
mode for ZFS: the recipient ZFS server will not be accessing the
data via ZFS from the local replicant live.

> And, in detail , it is not clear  if the receiving ZFS file system 
> could be used regularly while it is in "receiving mode":
> in poor words is it possible to read and export in nfs,   files from 
> a  ZFS file system while it is receiving update from  another  ZFS send ?
>
> Clearly  until the new updates are received and applied the old copy 
> would be used
>

If your solution requires simultaneous access of the same files
hosted by different servers without shared storage, then you are
describing a distributed or parallel file system, not ZFS.  If those
are the requirements, then perhaps Lustre or NFS v4.1 is a better
solution.

If the solution requires high availability using replication, then a
Solaris Cluster Geo Edition with AVS is a viable option.
 -- richard

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