Re: server restore behavior
If at all possible, yes. But you could get into a scenario where one session is waiting for a tape drive, but not the tape in question, AND it has been waiting longer than any other session. If so, the tape will dismount and the other tape will mount for the long-waiting session. And the first tape will remount later, for some other session. But for any given session, the tape will mount once unless pre-empted by a higher priority process (IIRC, the only process with a higher priority than a restore is a TSM database backup). Back in our first three years of D/R we had four DLT-7000 drives in our hotsite contract with no library, so we configured a 'manual' library with 4 tape drives. We got intimately acquainted with the TSM tape handling process as a result. Tom Kauffman NIBCO, Inc -Original Message- From: ADSM: Dist Stor Manager [mailto:[EMAIL PROTECTED] On Behalf Of Laura Mastandrea Sent: Friday, August 18, 2006 12:41 PM To: ADSM-L@VM.MARIST.EDU Subject: Re: server restore behavior We just had a DRP test and this question came up and I'd like confirmation that I'm reading your remark correct. TSM, on a restore, will mount a tape once and take all the files off of once? thx To ADSM-L@VM.MARIST.EDU cc From Sent by Kauffman, Tom [EMAIL PROTECTED] on 08/18/2006 11:30 AM ADSM: Dist Stor Manager ADSM-L@VM.MARIST.EDU Subject Re: [ADSM-L] server restore behavior Please respond to ADSM: Dist Stor Manager ADSM-L@VM.MARIST.EDU TSM will mount and start as many sessions as possible, and the rest will be in 'wait media' state until the tape they need (or a tape drive) becomes available. Given your scenarion, you may have one session reading tape and the other four waiting for access to the same tape. When the first session has retrieved ALL the files it needs from the first tape, it will go to the second (if not in use) and the session that has been waiting the longest will now get access to that first tape. Tom Kauffman NIBCO, Inc -Original Message- From: ADSM: Dist Stor Manager [mailto:[EMAIL PROTECTED] On Behalf Of Troy Frank Sent: Friday, August 18, 2006 12:23 PM To: ADSM-L@VM.MARIST.EDU Subject: server restore behavior This is more of a curiosity question than a problem. In a multiple-client restore scenario where you start up say 5 restores at once from different nodes (with 4 tape drives, and resourceutilization set to 4 on nodes), how does the server process the request? Technically, data from all 5 nodes are probably on a lot of the same tapes. Does it A) mount each tape exactly once, getting all data for all running restores off that tape before unmounting. B) Process the restores relatively serially for each node, giving each all 4 drives until completed. Unmounting/remounting the same tapes multiple times. C) Only give each node 1 tape drive to work with, which will effectively ellicit behavior very similiar to option B. Or does it do something different than any of these? Confidentiality Notice follows: The information in this message (and the documents attached to it, if any) is confidential and may be legally privileged. It is intended solely for the addressee. Access to this message by anyone else is unauthorized. If you are not the intended recipient, any disclosure, copying, distribution or any action taken, or omitted to be taken in reliance on it is prohibited and may be unlawful. If you have received this message in error, please delete all electronic copies of this message (and the documents attached to it, if any), destroy any hard copies you may have created and notify me immediately by replying to this email. Thank you. CONFIDENTIALITY NOTICE: This email and any attachments are for the exclusive and confidential use of the intended recipient. If you are not the intended recipient, please do not read, distribute or take action in reliance upon this message. If you have received this in error, please notify us immediately by return email and promptly delete this message and its attachments from your computer system. We do not waive attorney-client or work product privilege by the transmission of this message. DISCLAIMER: This communication, along with any documents, files or attachments, is intended only for the use of the addressee and may contain legally privileged and confidential information. If you are not the intended recipient, you are hereby notified that any dissemination, distribution or copying of any information contained in or attached to this communication is strictly prohibited. If you have received this message in error, please notify the sender immediately and destroy the original communication and its attachments without reading, printing or saving in any manner. This communication does not form any contractual obligation on behalf of the sender or, the sender's employer
Re: server restore behavior
So from the sound of it, a slightly less optimal version of Method A gets used. It will keep one tape mounted until all running or MediaW sessions get their crack at it, but while those other sessions are waiting for access to the tape they won't move on to attempt getting data from other tapes. [EMAIL PROTECTED] 08/18/06 11:30 AM TSM will mount and start as many sessions as possible, and the rest will be in 'wait media' state until the tape they need (or a tape drive) becomes available. Given your scenarion, you may have one session reading tape and the other four waiting for access to the same tape. When the first session has retrieved ALL the files it needs from the first tape, it will go to the second (if not in use) and the session that has been waiting the longest will now get access to that first tape. Tom Kauffman NIBCO, Inc -Original Message- From: ADSM: Dist Stor Manager [mailto:[EMAIL PROTECTED] On Behalf Of Troy Frank Sent: Friday, August 18, 2006 12:23 PM To: ADSM-L@VM.MARIST.EDU Subject: server restore behavior This is more of a curiosity question than a problem. In a multiple-client restore scenario where you start up say 5 restores at once from different nodes (with 4 tape drives, and resourceutilization set to 4 on nodes), how does the server process the request? Technically, data from all 5 nodes are probably on a lot of the same tapes. Does it A) mount each tape exactly once, getting all data for all running restores off that tape before unmounting. B) Process the restores relatively serially for each node, giving each all 4 drives until completed. Unmounting/remounting the same tapes multiple times. C) Only give each node 1 tape drive to work with, which will effectively ellicit behavior very similiar to option B. Or does it do something different than any of these? Confidentiality Notice follows: The information in this message (and the documents attached to it, if any) is confidential and may be legally privileged. It is intended solely for the addressee. Access to this message by anyone else is unauthorized. If you are not the intended recipient, any disclosure, copying, distribution or any action taken, or omitted to be taken in reliance on it is prohibited and may be unlawful. If you have received this message in error, please delete all electronic copies of this message (and the documents attached to it, if any), destroy any hard copies you may have created and notify me immediately by replying to this email. Thank you. CONFIDENTIALITY NOTICE: This email and any attachments are for the exclusive and confidential use of the intended recipient. If you are not the intended recipient, please do not read, distribute or take action in reliance upon this message. If you have received this in error, please notify us immediately by return email and promptly delete this message and its attachments from your computer system. We do not waive attorney-client or work product privilege by the transmission of this message. Confidentiality Notice follows: The information in this message (and the documents attached to it, if any) is confidential and may be legally privileged. It is intended solely for the addressee. Access to this message by anyone else is unauthorized. If you are not the intended recipient, any disclosure, copying, distribution or any action taken, or omitted to be taken in reliance on it is prohibited and may be unlawful. If you have received this message in error, please delete all electronic copies of this message (and the documents attached to it, if any), destroy any hard copies you may have created and notify me immediately by replying to this email. Thank you.
Re: server restore behavior
On Fri, 18 Aug 2006 12:30:08 -0400, Kauffman, Tom [EMAIL PROTECTED] said: TSM will mount and start as many sessions as possible, and the rest will be in 'wait media' state until the tape they need (or a tape drive) becomes available. Given your scenarion, you may have one session reading tape and the other four waiting for access to the same tape. When the first session has retrieved ALL the files it needs from the first tape, it will go to the second (if not in use) and the session that has been waiting the longest will now get access to that first tape. Several important points: The session that has been waiting the longest will get access to the tape -drive-, and if the longest-waiting session desires the mounted tape, that's all good. But the chances of that aren't great: each restore will calclulate its' list of desired tapes and its' desired order independantly, and each one will walk through that order linearly. Period. (last time I checked). This means that if hosts A and B both want tapes T0 and T1, and they both pick that order, and A gets T0 first, B will not fall back to deal with T1 before it blocks on T0 access. That dynamic reordering of work is just not something TSM does at the moment, and I can't blame them too much. Sounds hard in most cases. Implications for the case Troy suggested (5 simultaneous restores, 4 tapes drives, many noncollocated tapes) are that it is extremely unlikely that any mounted tape will be cleanly passed from one restore process to another; transitions will usually require a dismount and a mount. As usual, anyone got evidence that TSM's gotten smarter since last I looked, shoot me down. - Allen S. Rout
Re: server restore behavior
AFAIK, it's first come first serve. - The different restore sessions will not talk to each other, and the TSM server will not coordinate their resource usage, so it's not A. - Since each session will compete for drives and get the next one available when they get up to bat, it's not B. - And since they all have resourceutilization 4, it's not C. In fact, I'd think it's quite unpredictable, because each client may have differing hardware capabilities, other network traffic will influence it, and what each client is restoring will affect how quickly it gets to the tape mount request(s). It would be nice, though, if the TSM server did coordinate the active sessions. Even nicer would be a facility to define a restore plan, assigning priorities and weights. I suppose you could hack something together with some fancy scripting and/or using an external scheduler like Control-M... but seems like it would be a lot of work. Robin Sharpe Berlex Labs Troy Frank [EMAIL PROTECTED] WISC.EDU To Sent by: ADSM: ADSM-L@VM.MARIST.EDU Dist Stor cc Manager [EMAIL PROTECTED] Subject .EDU server restore behavior 08/18/2006 12:22 PM Please respond to ADSM: Dist Stor Manager [EMAIL PROTECTED] .EDU This is more of a curiosity question than a problem. In a multiple-client restore scenario where you start up say 5 restores at once from different nodes (with 4 tape drives, and resourceutilization set to 4 on nodes), how does the server process the request? Technically, data from all 5 nodes are probably on a lot of the same tapes. Does it A) mount each tape exactly once, getting all data for all running restores off that tape before unmounting. B) Process the restores relatively serially for each node, giving each all 4 drives until completed. Unmounting/remounting the same tapes multiple times. C) Only give each node 1 tape drive to work with, which will effectively ellicit behavior very similiar to option B. Or does it do something different than any of these? Confidentiality Notice follows: The information in this message (and the documents attached to it, if any) is confidential and may be legally privileged. It is intended solely for the addressee. Access to this message by anyone else is unauthorized. If you are not the intended recipient, any disclosure, copying, distribution or any action taken, or omitted to be taken in reliance on it is prohibited and may be unlawful. If you have received this message in error, please delete all electronic copies of this message (and the documents attached to it, if any), destroy any hard copies you may have created and notify me immediately by replying to this email. Thank you.
Re: server restore behavior
TSM will mount and start as many sessions as possible, and the rest will be in 'wait media' state until the tape they need (or a tape drive) becomes available. Given your scenarion, you may have one session reading tape and the other four waiting for access to the same tape. When the first session has retrieved ALL the files it needs from the first tape, it will go to the second (if not in use) and the session that has been waiting the longest will now get access to that first tape. Tom Kauffman NIBCO, Inc -Original Message- From: ADSM: Dist Stor Manager [mailto:[EMAIL PROTECTED] On Behalf Of Troy Frank Sent: Friday, August 18, 2006 12:23 PM To: ADSM-L@VM.MARIST.EDU Subject: server restore behavior This is more of a curiosity question than a problem. In a multiple-client restore scenario where you start up say 5 restores at once from different nodes (with 4 tape drives, and resourceutilization set to 4 on nodes), how does the server process the request? Technically, data from all 5 nodes are probably on a lot of the same tapes. Does it A) mount each tape exactly once, getting all data for all running restores off that tape before unmounting. B) Process the restores relatively serially for each node, giving each all 4 drives until completed. Unmounting/remounting the same tapes multiple times. C) Only give each node 1 tape drive to work with, which will effectively ellicit behavior very similiar to option B. Or does it do something different than any of these? Confidentiality Notice follows: The information in this message (and the documents attached to it, if any) is confidential and may be legally privileged. It is intended solely for the addressee. Access to this message by anyone else is unauthorized. If you are not the intended recipient, any disclosure, copying, distribution or any action taken, or omitted to be taken in reliance on it is prohibited and may be unlawful. If you have received this message in error, please delete all electronic copies of this message (and the documents attached to it, if any), destroy any hard copies you may have created and notify me immediately by replying to this email. Thank you. CONFIDENTIALITY NOTICE: This email and any attachments are for the exclusive and confidential use of the intended recipient. If you are not the intended recipient, please do not read, distribute or take action in reliance upon this message. If you have received this in error, please notify us immediately by return email and promptly delete this message and its attachments from your computer system. We do not waive attorney-client or work product privilege by the transmission of this message.
Re: server restore behavior
We just had a DRP test and this question came up and I'd like confirmation that I'm reading your remark correct. TSM, on a restore, will mount a tape once and take all the files off of once? thx To ADSM-L@VM.MARIST.EDU cc From Sent by Kauffman, Tom [EMAIL PROTECTED] on 08/18/2006 11:30 AM ADSM: Dist Stor Manager ADSM-L@VM.MARIST.EDU Subject Re: [ADSM-L] server restore behavior Please respond to ADSM: Dist Stor Manager ADSM-L@VM.MARIST.EDU TSM will mount and start as many sessions as possible, and the rest will be in 'wait media' state until the tape they need (or a tape drive) becomes available. Given your scenarion, you may have one session reading tape and the other four waiting for access to the same tape. When the first session has retrieved ALL the files it needs from the first tape, it will go to the second (if not in use) and the session that has been waiting the longest will now get access to that first tape. Tom Kauffman NIBCO, Inc -Original Message- From: ADSM: Dist Stor Manager [mailto:[EMAIL PROTECTED] On Behalf Of Troy Frank Sent: Friday, August 18, 2006 12:23 PM To: ADSM-L@VM.MARIST.EDU Subject: server restore behavior This is more of a curiosity question than a problem. In a multiple-client restore scenario where you start up say 5 restores at once from different nodes (with 4 tape drives, and resourceutilization set to 4 on nodes), how does the server process the request? Technically, data from all 5 nodes are probably on a lot of the same tapes. Does it A) mount each tape exactly once, getting all data for all running restores off that tape before unmounting. B) Process the restores relatively serially for each node, giving each all 4 drives until completed. Unmounting/remounting the same tapes multiple times. C) Only give each node 1 tape drive to work with, which will effectively ellicit behavior very similiar to option B. Or does it do something different than any of these? Confidentiality Notice follows: The information in this message (and the documents attached to it, if any) is confidential and may be legally privileged. It is intended solely for the addressee. Access to this message by anyone else is unauthorized. If you are not the intended recipient, any disclosure, copying, distribution or any action taken, or omitted to be taken in reliance on it is prohibited and may be unlawful. If you have received this message in error, please delete all electronic copies of this message (and the documents attached to it, if any), destroy any hard copies you may have created and notify me immediately by replying to this email. Thank you. CONFIDENTIALITY NOTICE: This email and any attachments are for the exclusive and confidential use of the intended recipient. If you are not the intended recipient, please do not read, distribute or take action in reliance upon this message. If you have received this in error, please notify us immediately by return email and promptly delete this message and its attachments from your computer system. We do not waive attorney-client or work product privilege by the transmission of this message. DISCLAIMER: This communication, along with any documents, files or attachments, is intended only for the use of the addressee and may contain legally privileged and confidential information. If you are not the intended recipient, you are hereby notified that any dissemination, distribution or copying of any information contained in or attached to this communication is strictly prohibited. If you have received this message in error, please notify the sender immediately and destroy the original communication and its attachments without reading, printing or saving in any manner. This communication does not form any contractual obligation on behalf of the sender or, the sender's employer, or the employer's parent company, affiliates or subsidiaries.
