LTO tape on SAS controller (only for one guest)

[spaceinvader]

Hi all!

There are issues with SAS LTO tapes on SAS controllers - I've read all community threads about tape drives (I suppose).

I've trouble to use a LTO-3 SAS tape drive in a Windows Server 2008 R2 guest with Backup Exec 12.5. The tape drive and tapes are regognized and some operations are working, but I've several problems with backup/restore tasks and so on ("wrong command" or similar - typical controller communication problems).

My config:

Supermicro H8DII+-F

Adaptec 51645 SAS/SATA RAID controller (for all system HDDs and the tape drive)

LTO-3 drive in an external enclosure: Tandberg Data 3500-LTO (like HP Ultrium 920 / EH847A)

VMware ESXi 4.0 Update 1 (before checked with "Update 0", too, same results)

- SCSI controller type for the guest: "LSI Logic SAS"

- tape device is added as "SCSI device 1" ("SCSI (0:1)") to the guest VM

Guest: Windows Server 2008 R2, all current updates applied

- SCSI driver: first used genuine lsi_sas.sys for "LSI Adapter, SAS 3000 series, ..." v1.28.xx

later updated to more current v1.30.2.0 (2009-01-30)

- Tandberg Data driver "td_ltohh.sys"

Backup Exec 12.5 SP3 (most current version)

- (perhaps additional tape driver tpfilter.sys)

On the same machine with Windows Server 2008 R2 installed directly (without VMware ESXi 4.0) this hardware setup is working (however with an updated Adaptec controller driver - with genuine WS 2008 R2 Adaptec driver it wasn't reliably working, too).

Has anybody some hints to get this setup working?

(Please do not recommend an additional SAS controller for the tape drive, like Adaptec 1045. That's not the way we want. - But reports of running setups with dediceted SAS controllers would be welcome, anyway! Even VMware DirectPass PCI pass-through setups.)

(It's not an option that a high quality 800 US $ Adaptec SAS RAID controller isn't able to drive standard SAS devices like tape drive, too. Standard SAS devices have to work like standard devices. We didn't be in the early 1990's! :smileywink: )

Thanks for any help/support!

[asatoran]

(Please do not recommend an additional SAS controller for the tape drive, like Adaptec 1045. That's not the way we want. - But reports of running setups with dediceted SAS controllers would be welcome, anyway! Even VMware DirectPass PCI pass-through setups.)

(It's not an option that a high quality 800 US $ Adaptec SAS RAID controller isn't able to drive standard SAS devices like tape drive, too. Standard SAS devices have to work like standard devices. We didn't be in the early 1990's! :smileywink: )

Do SAS tape drives have the same recommendations as SCSI tape drives? Normal recommendation is to never put the the SCSI tape drive on the same channel as the hard drives and never a RAID controller. Does that apply to SAS? I'm still reading recommendations to not put SAS tape drives on RAID controllers, but I don't know if that's from experience or just "SAS is SCSI so same recommendation." At the very least, have you tried moving the tape drive to a different port connector or channel?

You would think that it should work as "standard devices", that was one of the selling points of the original SCSI, but as we can see, that's not what happened, especially with RAID controllers and parallel SCSI tape drives. So it may not be what you want, but if you do need a separate controller, well, it is what it is. :smileysad:

[Texiwill]

Hello,

Tape devices need to be placed on Non-Raid SCSI controllers. It may work from some SAS (non-RAID) controllers as well, but the recommendation is still SCSI Non-Raid controllers. You also may not want a tape device on your SAS RAID controller for a number of reasons but performance would be one of them for me. Depends on the SAS card.

But last time I looked (granted it was during the Beta) this was still a limitation.

Also for the VM, you need to put the tape device on another 'SCSI' or 'SAS' adapter and not on the same one with your vmdks. In addition, the SCSI ID should match the SCSI ID of the tape device.

Best regards,
Edward L. Haletky VMware Communities User Moderator, VMware vExpert 2009

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[spaceinvader]

Hi Texiwill!

Thank you for your answer - and don't be offended by my jokes!

Tape devices need to be placed on Non-Raid SCSI controllers. It may work from some SAS (non-RAID) controllers as well, but the recommendation is still SCSI Non-Raid controllers.

(P-)SCSI non-RAID controllers!? Why to use 1990 techniques? (Except garbage recycling. :smileywink: )

Sorry, I don't want to use old tape drive solutions due to outdated "recommendations" from backward driver developers.

You also may not want a tape device on your SAS RAID controller for a number of reasons but performance would be one of them for me. Depends on the SAS card.

I may. But what performance do you mean? The 3GB/s SAS channel speed? The 4GB/s (full-duplex) PCIe 2.0 x8 speed? (Neither HDDs nor tapes come to this speed. My LTO-3 drive is acting typically at 60 to 120 MB/s. This should be processed on the SAS sideband channel without notice by the server. :smileywink: )

Shouldn't I connect more than one or two HDDs to the 20 channel :smileyalert: SAS controller because of the 4GB/s PCIe limit? :smileywink:

I suppose there are rare scenarios where a 20 channel SAS RAID controller is fully utilizated and tape data traffic is a problem. (Seems to be suppositions amd experiences from the early 1990's? :smileywink: )

I only can give you reasons why I want my tape drive on my SAS RAID controller: plug in, running, ready, easy and usable (unfortunately the inferior drivers are avoiding this simple scenario). Thoughts about reasons against connecting to this controller can be done by bored scientists. :smileywink:

Also for the VM, you need to put the tape device on another 'SCSI' or 'SAS' adapter and not on the same one with your vmdks. In addition, the SCSI ID should match the SCSI ID of the tape device.

I don't see reasons for separating things at the guests, too (aside from inferior driver quality).

There are no IDs with SAS, only virtual IDs by VMwares virtualized hardware (sawn by the guest), but with guests SAS controller there are no IDs, too.

Thank you for your readiness to help, anyway!

[spaceinvader]

Hi asatoran!

Do SAS tape drives have the same recommendations as SCSI tape drives? Normal recommendation is to never put the the SCSI tape drive on the same channel as the hard drives and never a RAID controller. Does that apply to SAS? I'm still reading recommendations to not put SAS tape drives on RAID controllers, but I don't know if that's from experience or just "SAS is SCSI so same recommendation."

I've no interest to scan all the thousands of documents from VMware to investigate all possible "recommendations" about tape drives. Additionaly infos about "supported" solutions are boring me. :smileywink:

At my point of view, all SCSI or SAS devices have to run. (The driver vendors shouldn't deliver such inferior quality.)

SAS is not P-SCSI. No combined channels (not in P-SCSI way, anyhow).

At the very least, have you tried moving the tape drive to a different port connector or channel?

The Adaptec 51646 is a 20 dedicated channel SAS controller, every "port" is a separate channel with a separate cable (respectively: multilane cable). No necessity to plug around the ports.

You would think that it should work as "standard devices", that was one of the selling points of the original SCSI, but as we can see, that's not what happened, especially with RAID controllers and parallel SCSI tape drives. So it may not be what you want, but if you do need a separate controller, well, it is what it is. :smileysad:

No! Never be satisfied with inferior developments!

By the way: I'm working on testing with a separate controller. What a trap: unfortunately I got an "unsupported" (I cannot

hear this word anymore!) Adaptec non-RAID SAS controller 1045.

[asatoran]

Do SAS tape drives have the same recommendations as SCSI tape drives? Normal recommendation is to never put the the SCSI tape drive on the same channel as the hard drives and never a RAID controller. Does that apply to SAS? I'm still reading recommendations to not put SAS tape drives on RAID controllers, but I don't know if that's from experience or just "SAS is SCSI so same recommendation."

I've no interest to scan all the thousands of documents from VMware to investigate all possible "recommendations" about tape drives. Additionaly infos about "supported" solutions are boring me. :smileywink:

I'm not talking about anything VMWare said. That's the advice I get from the industry in general. Various "experts" still say no tape drives on RAID, even SAS drives. Again, I still have some uncertainty as to if that is truly from experience with SAS tape drives. But that was NOT from any VMWare documentation.

At my point of view, all SCSI or SAS devices have to run. (The driver vendors shouldn't deliver such inferior quality.)

>> SAS is not P-SCSI. No combined channels (not in P-SCSI way, anyhow).

At the very least, have you tried moving the tape drive to a different port connector or channel?

The Adaptec 51646 is a 20 dedicated channel SAS controller, every "port" is a separate channel with a separate cable (respectively: multilane cable). No necessity to plug around the ports.

You would think that it should work as "standard devices", that was one of the selling points of the original SCSI, but as we can see, that's not what happened, especially with RAID controllers and parallel SCSI tape drives. So it may not be what you want, but if you do need a separate controller, well, it is what it is. :smileysad:

No! Never be satisfied with inferior developments!

By the way: I'm working on testing with a separate controller. What a trap: unfortunately I got an "unsupported" (I cannot

hear this word anymore!) Adaptec non-RAID SAS controller 1045.

I never said I was "satisfied". As I said, the original selling point in SCSI years ago was that it was one bus that could handle anything. But that's not what happened. So it wouldn't surprise me that SAS has some limitations. I wouldn't be happy with it, but it wouldn't surprise me.

I had a bear of a time with getting my HP 920 uSCSI320 drive to work on ESX 3.5 & 4.0. I'm using a Adaptec 29320LPE, which works, but is technically not supported. I got this controller to replace a HP branded LSI that was causing the ESX host to PSOD when the tape drive was accessed. Because a similar Adaptec controller is on the HCL I was hoping this one would be close because it's not in the budget to replace the tape drive at this time. But the experience is leading me toward iSCSI based tape and VTL drives when the time comes to replace this drive. Am I satisfied with not using passthrough? No. But the elimination of the stress of uncertainty of passthrough during the replacement of the tape drivewill likely make me more satisfied with the replacement project overall when. the time comes. Basically, decide which battles you want to fight. I want to spend my time at the beach, not fighting an unstable machine. :smileywink:

[Texiwill]

Hello,

Unfortunately what you get is not what you want. THere are certain limitations with HBAs when using tape devices... That is a given, working within them is the issue.

As for performance, sharing TAPE and RAID traffic on one card where both are heavy hitters. While you have many channels on the card, you still only have one bus in use to get that data to the card.... I tend to want to separate that.

Best regards,
Edward L. Haletky VMware Communities User Moderator, VMware vExpert 2009

Virtualization Practice Analyst[/url]
Now Available: 'VMware vSphere(TM) and Virtual Infrastructure Security'[/url]
Also available 'VMWare ESX Server in the Enterprise'[/url]
[url=http://www.astroarch.com/wiki/index.php/Blog_Roll]SearchVMware Pro[/url]|Blue Gears[/url]|Top Virtualization Security Links[/url]|
[url=http://www.astroarch.com/wiki/index.php/Virtualization_Security_Round_Table_Podcast]Virtualization Security Round Table Podcast[/url]