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Multiple hosts to multiple SAS drives in MSL4048?

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Paul_637
Regular Advisor

Multiple hosts to multiple SAS drives in MSL4048?

Given an MSL4048 with two LTO-4 SAS drives, do they *have* to be connected to the same host, or can they be connected to by two different hosts, with tape requests "intellilgentlly" managed by the library mechanism?

I'm looking to make best use of a hardware setup I've "inherited" where a central backup server was configured with the above connected to a single server but with most of the data external to this server (i.e. LAN-based backup) they're simmply never going to be able to suck data *into* the server (over the LAN) quickly enough to make reasonable use of two LTo-4 drives! (even feeding a single LTO-4 drive would be hard enough!)

So, are two servers to one (SAS-based) library a feasible option?

Regards,

Paul
18 REPLIES
Paul_637
Regular Advisor

Re: Multiple hosts to multiple SAS drives in MSL4048?

Sorry, these are actually SCSI drives I believe although that probably shouldn't make any difference.
kunalsahoo
Valued Contributor

Re: Multiple hosts to multiple SAS drives in MSL4048?

Hi Paul,

This library has to be connected to 1 server.
if you check the SAS cable, the 4 port side will be connected to the drives and the other side will go to the server.

specially in MSL4048 library there is a concept of master and slave drive.
the robot gets scsi ID from the master drive only.

so if you connect 2 drives to 2 diffrent servers, only one can see and access the robotic controller to which master drive is connected and the other drive will act as god as a stand alone drive to the other server......
Paul_637
Regular Advisor

Re: Multiple hosts to multiple SAS drives in MSL4048?

Ah, damn! Is that still the case with SCSI drives (as I updated above)?

I.e. are the SCSI drives daisy-chained together to a single connection to the server?

(I'd take a look myself but the drive is 100 miles away! :)

Paul
kunalsahoo
Valued Contributor

Re: Multiple hosts to multiple SAS drives in MSL4048?

Hi Paul,

if you are using MSL 4048 library then there is no concept of daisy chaining.....
with Sas drives connected the SAS ports from Drives will directly go to the SERVER SAS card...
Paul_637
Regular Advisor

Re: Multiple hosts to multiple SAS drives in MSL4048?

Sorry, perhaps I'm confusing things in this thread.

I realised after posting the original message that the drives are actually U320 SCSI-based rather than SAS-based after all.

So, bearing in mind I've found in a Quick STart guide a line saying along the lines that two SCSI drives should not be connected to the same HBA, I'm hoping that means that SCSI drives can be connected to different hosts?
kunalsahoo
Valued Contributor
Solution

Re: Multiple hosts to multiple SAS drives in MSL4048?

Ahh...........

No paul...any point of time you cannot connect it to 2 different servers.


1 You are correct that each drive should go to separate card.

2 Both the cards has to be in same server as i mentioned earlier MSL 4048 library have master and slave drive concept.....server talks to robot via master drive as master drive and robot will be in same scsi bus.

3 If you connect both the drives to diffrent servers then 1 server will see the Robot abd the master drive and the other server will see the other drive(slave) but cannot use the robot ......hope you are clear now
Paul_637
Regular Advisor

Re: Multiple hosts to multiple SAS drives in MSL4048?

Ah, right, that's fine then, makes it completely clear, unfortunately :(
kunalsahoo
Valued Contributor

Re: Multiple hosts to multiple SAS drives in MSL4048?

is the data to be backed up in an external storage box over FC san ?
Paul_637
Regular Advisor

Re: Multiple hosts to multiple SAS drives in MSL4048?

It's a horrible mess they've cobbled together!

From what I can make out, they have a number of clustered-pairs of servers (at least 3 2-node clusters) each with it's own direct-attach MSA2xxxFC and at the other end of the room they apparently have a huge EVA with SAN switches, but again only connected to a couple of hosts!!!

Then they have around 6 individual LTO-3/4 tape drives scattered around the servers, trying to cram it all through Backup Exec and wondering why they're only getting 955Mb/min onto the backup server!

I'm trying to look at options to get them moved over to HPDP where at least they can multiplex backups but they simply aren't going to be able to do much to push data through to this server (with two drives) unless they start looking at 10Gb networks.

Talk about wasting money hand-over-fist...

(I've been working on this account for 4 weeks now and trying to get them to do "sensible" IT!).

Paul
kunalsahoo
Valued Contributor

Re: Multiple hosts to multiple SAS drives in MSL4048?

Sounds complected setup....but i would suggest one simple thing....that will make your life easier...

connect this backup server to the san , all the boxes you said have snapshot facility...
take snapshot of each Lun to be backed up....present them to this server take backup unmount snap shot and delete it.....

this needs to be done every time though :(
Paul_637
Regular Advisor

Re: Multiple hosts to multiple SAS drives in MSL4048?

That's the sort of thing I'm looking to propose. Depends what size of SAN switch they have (and how many ports licensed).

One thing I haven't personally worked with though is the snapshot side of things - does that tend to be a licensed option or is it included in the MSAs? I know it's an additional license on the EVA side of things.

I still need to get up to speed on the differences between the MSA2xxx & the MSA1000's which was the previous MSA I worked with but I know it's a rather different beast now!

Paul
kunalsahoo
Valued Contributor

Re: Multiple hosts to multiple SAS drives in MSL4048?

Hi .........

In MSA2000 you have some snap shot facility ...
with default license....to get more capacity u have to purchase License...


Marino Meloni_1
Honored Contributor

Re: Multiple hosts to multiple SAS drives in MSL4048?

I didn't read all the thread, but I understand you have a 4048 with two drives

You may connect this library one drive to one server and another drive to second server

The main problem is that you need an enterprise backup application or a backup application that is able to support this configuration.

You should have one server that manages both drives, one using the direct attached and the other using it via the media server.

Another option is to partition the MSL4048 and have two virtual libraries one independent of the other each with own robot and drive, and dedicated magazine. You only need latest FW for that, and then you can partition it from the GUI
Paul_637
Regular Advisor

Re: Multiple hosts to multiple SAS drives in MSL4048?

That sounds extremely promising Marino!

Can I confirm that this *isn't* only possible with FC drives? (These are U320 SCSI).

Would one need to purchase an additional robot mechanism or similar then as well?

I'm consious that most (all?) "shared tape" solutions I've found so far are always refering to FC drives (which I'm aware of and have dealt with in the past, although only a single-drive per library).

Any pointers to documentation relating to partitioning info would be extremely appreciated!

Paul
Marino Meloni_1
Honored Contributor

Re: Multiple hosts to multiple SAS drives in MSL4048?

Paul_637
Regular Advisor

Re: Multiple hosts to multiple SAS drives in MSL4048?

Thanks for that, very useful for the logical configuration!

However, there's no mention of host connectivity in there but I'll try more searching around "logical library" rather than "partition" which might reveal more...

Paul
Marino Meloni_1
Honored Contributor

Re: Multiple hosts to multiple SAS drives in MSL4048?

In a partitioned library, each host will have dedicated drive, and (due to the partitioning) dedicated virtual picker, plus dedicated slots.
So doesn't matter what you connect to the library, as each virtual is like a single library, you can attach different OS with differnt Backup application, and running both at the same time (only some delay when queuing robot comands, obvioulsy)
Paul_637
Regular Advisor

Re: Multiple hosts to multiple SAS drives in MSL4048?

Fantastic - that's exactly what I wanted to hear! Thanks for the clarification!

Now to get permission to test....

:)