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Re: 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 18
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