update issues

[FthrJACK]

Hi,

Im trying out Istorage since i found Starwind to be totaly unreliable, it would crash and yet seem to be all running fine, yet it wasnt.


I quite like istorage, it has some nice features, nice interface etc. However i have a problem...

I created a Partition-to-disk bridged device, and then using Microsoft targeter i set the drive on two other machines as drive Q.
All seems to work fine... permissions set, both machines have write access.


I then create a file or folder in drive Q on one machine, go to the second machine and open drive Q..... empty. Hit refresh a load of times... still empty.
close windows explorer, reopen drive Q.. still empty. So then on machine 2 i write a file to drive Q, go to machine 1.... it only shows the origional file i wrote while on that machine.

In short the only way to get the file to show to both machines seams to be to disconnect the iSCSI session, reconnect. And that doesent always seem to work...
Ive tried this with "Hold and Update" turned on and off, even removed the partition/drive and remade it with this setting OFF, and it still does it.


Any help much appreciated

[Olivia (staff)]

Hi, it is not a issue but:
iStorage Server is a storage solution so it works at the block level, so updates can not be real-time, because of the file system cache. When you copy data files to a initiator with full access:
1, The target can't use these data files until computer restarts, but we provides hold and update mechanism so that the restart is not required if there is no files on the drive is opened and no application is using the drive.
2, Other initiators need to re-log on to the target, then the data files can be updated.
If you want update from one initiator to others real-time, you need not only a storage solution, but also a file sharing solution, such as Windows Share Folder, NAS etc.

[FthrJACK]

this behaviour only happens with iStorage?!

ive used Sanmelody and Starwind - if i set up a shared drive with those, then update a file (create a file folder etc) on one machine to the drive.... i will be able to see the file on all machines.

without rebooting / relogging.


This is how anyone would EXPECT it to work. Otherwise --- whats the point in it?
You cant get clustering to work without this, as the cluster machines need to see the files and folders there. Likewise for exchange or SQL.

I dont see the point in iSCSI software that does cached writes to the target like iStorage does - its broken like it is. As i said.. you cant use clustering, which is one of the main reasons people use iSCSI.


Unless im missing something here?

[selskiecsso]

This makes me very excited, but it seems not possible.
I've deployed and tested with iSCSI solution for several years, all my customers have 30-500 computers share from one server, the iSCSI is very popular in our country, but all of us haven’t got a perfect solution.
The iSCSI Server itself can’t handle with it. But it is not an issue for the clustering, because the clustering software will do the Synchronization things.
It is also a issue from starwnd,
http://www.starwindsoftware.com/forums/ ... t1392.html

[KOOLER]

Well... I have two bad news for you man ))

1) You're a liar... I mean it! What you THINK worked with StarWind and SANmelody (the only problem with this stuff it's OVERPRICED as it still runs circles around ANY iSCSI target on the market
when talking about performance) could actually NEVER work. Having more then one writer on non-clustered file system like NTFS is is going
to trash metadata consistantly and pretty fast. This approach does not work with any iSCSI target (or other SAN storage like FC or AoE) by
design and it's what people were trying to tell you ))

2) You really don't understand the technology... Having multiple writers is NOT a cluster and having shared folder is NOT a cluster approach either.

What COULD work for you (if you would be a real user and not iSCSI Cake affilated poster as these guys LOVE posting shit about competitors on
the Internet, something what you do now) is having either multi-writer file system (Veritas or maybe DataPlow SFS or GFS) or having distributed
lock manager like the one MetaSAN from Tiger Technologies guys sell. Local support staff are pretty new kids on the block so it's forgivable for
them to say "No, we don't do it" instead of "Yes, we do it but with the help of third-party software" ))


These ones are iSCSI target agnostic and should be OK for any iSCSI target with SCSI-2 style reservations.

Adios amigo!!

this behaviour only happens with iStorage?!

ive used Sanmelody and Starwind - if i set up a shared drive with those, then update a file (create a file folder etc) on one machine to the drive.... i will be able to see the file on all machines.

without rebooting / relogging.


This is how anyone would EXPECT it to work. Otherwise --- whats the point in it?
You cant get clustering to work without this, as the cluster machines need to see the files and folders there. Likewise for exchange or SQL.

I dont see the point in iSCSI software that does cached writes to the target like iStorage does - its broken like it is. As i said.. you cant use clustering, which is one of the main reasons people use iSCSI.


Unless im missing something here?

[selskiecsso]

I know metaSAN, but it is not a real solution, because customers need to pay extra fees and much more than the iSCSI target.
None of my customer can accept it as far, most of them all think the iSCSI can do, I am very tired to persuade them.
Do not think that each customer are experts, you need to help them.

[selskiecsso]

One more important reason, for example:
We have three computers, Server, NodeA and NodeB.
When an application open a file on NodeA with exclusive access, the applications on NodeB can’t access it if you using metaSAN or other NFS and even of Windows share folder. But we need NodeA can exclusive access a file which NodeB can also exclusive it. Because there are hundreds of computers share from one drive and running the same one application or came at the same time.
So we like KernSafe Virtual Write (INetDisk), iSCSI cake also provides the similar technology, but it running at server side, the burden of server is very heavy.
Nevertheless, there is also a problem when you update files to server, all the clients can’t use it until re-mount.

[KOOLER]

Distributed lock arbiters ARE solutions. If you cannot afford them it's your and your customers problem. It's like saying "Ferrari is not a car as I cannot afford it".

"No money" means "go Linux". It has free iSCSI targets (IET is a real solution most of the commercial Linux-inside appliances are built on) and it has free GFS solving all your tasks.

I know metaSAN, but it is not a real solution, because customers need to pay extra fees and much more than the iSCSI target.
None of my customer can accept it as far, most of them all think the iSCSI can do, I am very tired to persuade them.
Do not think that each customer are experts, you need to help them.

[KOOLER]

You need to understand your task initially. If you need shared base + per-customer unique updates - go COW, if you need true concurrent access - any SAN capable file system will do it.
MelioFS from Sanbolic for example has "per-region" rathen then "per-file" unique access.

One more important reason, for example:
We have three computers, Server, NodeA and NodeB.
When an application open a file on NodeA with exclusive access, the applications on NodeB can’t access it if you using metaSAN or other NFS and even of Windows share folder. But we need NodeA can exclusive access a file which NodeB can also exclusive it. Because there are hundreds of computers share from one drive and running the same one application or came at the same time.
So we like KernSafe Virtual Write (INetDisk), iSCSI cake also provides the similar technology, but it running at server side, the burden of server is very heavy.
Nevertheless, there is also a problem when you update files to server, all the clients can’t use it until re-mount.

[selskiecsso]

hah, the starwnd guy moves here.
If something is too expensive, it is surely not a solution, COW is not a solution for us too. THANKS.