So if a source/destination pair is doing a snapmirror update and the current update is not complete before a new update is requested, what is the behavior? Does it queue the second snapmirror update and just update it when the first completes?
I understand the behavior when updates are done by the scheduler on the array itself as per snapmirror.conf. In this case it queues the updates but only to a maximum of three.
"If an update is in progress when another is scheduled to occur, SnapMirror starts another transfer as soon as the transfer is complete. However, if three updates pass while the current transfer is in progress, SnapMirror does only one more update; it does not go back and run updates that have been made obsolete by those scheduled later."
But I'm not talking updates initiated by the scheduler on the array itself.
I'm really asking about something like SME performing a backup and requesting an update. The snapmirror update here is functionally equivalent to issuing a snapmirror update command manually. Suppose the mirror does not complete before the next backup and subsequent update request is made (or snapmirror update command issued manually). What if the rate of data change exceeds the ability of network to complete the mirror or if the WAN link to the DR site is just too darn slow? Do the updates queue on the destination and snapshots build up on the source indefinitely? Or do manual or snapmanager initiated updates follow the "queue to three and then give up" rule above?
Anyone know?
Timothy L. Hollingworth Sr. Network Engineer ePlus Technology, inc. 511 Davis Drive Suite 350 Morrisville, NC 27560 678.462.6698 (Direct/Cell) thollingworth@eplus.com www.eplus.com
The information contained in this electronic transmission and any attachments hereto may be considered proprietary and confidential. Unauthorized distribution of this material to anyone other than the addressed is prohibited. Any disclosure, distribution or use of this transmission for any reason other than their intended purpose is prohibited.
The manual snapmirror update command will fail with a snapmirror busy error.
On 3/23/11 9:48 AM, "Timothy Hollingworth" thollingsworth@EPLUS.com wrote:
So if a source/destination pair is doing a snapmirror update and the current update is not complete before a new update is requested, what is the behavior? Does it queue the second snapmirror update and just update it when the first completes?
I understand the behavior when updates are done by the scheduler on the array itself as per snapmirror.conf. In this case it queues the updates but only to a maximum of three.
"If an update is in progress when another is scheduled to occur, SnapMirror starts another transfer as soon as the transfer is complete. However, if three updates pass while the current transfer is in progress, SnapMirror does only one more update; it does not go back and run updates that have been made obsolete by those scheduled later."
But I'm not talking updates initiated by the scheduler on the array itself.
I'm really asking about something like SME performing a backup and requesting an update. The snapmirror update here is functionally equivalent to issuing a snapmirror update command manually. Suppose the mirror does not complete before the next backup and subsequent update request is made (or snapmirror update command issued manually). What if the rate of data change exceeds the ability of network to complete the mirror or if the WAN link to the DR site is just too darn slow? Do the updates queue on the destination and snapshots build up on the source indefinitely? Or do manual or snapmanager initiated updates follow the "queue to three and then give up" rule above?
Anyone know?
Timothy L. Hollingworth Sr. Network Engineer ePlus Technology, inc. 511 Davis Drive Suite 350 Morrisville, NC 27560 678.462.6698 (Direct/Cell) thollingworth@eplus.com
www.eplus.com
The information contained in this electronic transmission and any attachments hereto may be considered proprietary and confidential. Unauthorized distribution of this material to anyone other than the addressed is prohibited. Any disclosure, distribution or use of this transmission for any reason other than their intended purpose is prohibited.
The current snapmirror will finish and then pick up again when the next scheduled transfer is supposed to happen.
i.e.: mirror takes from 2pm-310pm (maybe due to a slow wan). If the schedule is for every hour, then the 3pm will be skipped and it will resume at 4pm
You can always look to silverpeak or riverbed to help speed up transfers over a WAN.
--tmac Tim McCarthy Principal Consultant
RedHat Certified Engineer 804006984323821 (RHEL4) 805007643429572 (RHEL5)
On Wed, Mar 23, 2011 at 12:48 PM, Timothy Hollingworth < thollingsworth@eplus.com> wrote:
So if a source/destination pair is doing a snapmirror update and the current update is not complete before a new update is requested, what is the behavior? Does it queue the second snapmirror update and just update it when the first completes?
I understand the behavior when updates are done by the scheduler on the array itself as per snapmirror.conf. In this case it queues the updates but only to a maximum of three.
"If an update is in progress when another is scheduled to occur, SnapMirror starts another transfer as soon as the transfer is complete. However, if three updates pass while the current transfer is in progress, SnapMirror does only one more update; it does not go back and run updates that have been made obsolete by those scheduled later."
But I'm not talking updates initiated by the scheduler on the array itself.
I'm really asking about something like SME performing a backup and requesting an update. The snapmirror update here is functionally equivalent to issuing a snapmirror update command manually. Suppose the mirror does not complete before the next backup and subsequent update request is made (or snapmirror update command issued manually). What if the rate of data change exceeds the ability of network to complete the mirror or if the WAN link to the DR site is just too darn slow? Do the updates queue on the destination and snapshots build up on the source indefinitely? Or do manual or snapmanager initiated updates follow the "queue to three and then give up" rule above?
Anyone know?
Timothy L. Hollingworth Sr. Network Engineer ePlus Technology, inc. 511 Davis Drive Suite 350 Morrisville, NC 27560 678.462.6698 (Direct/Cell) thollingworth@eplus.com
www.eplus.com
The information contained in this electronic transmission and any attachments hereto may be considered proprietary and confidential. Unauthorized distribution of this material to anyone other than the addressed is prohibited. Any disclosure, distribution or use of this transmission for any reason other than their intended purpose is prohibited.
Unless something has changed in the last year, this is not the expected behavior. Assume hourly snapmirrors based on snapmirror.conf schedule, at 1pm, 2pm, 3pm, 4pm, etc… Assume most snapmirrors take 30mins to run. Something makes the 2pm snapmirror take 70 minutes. The 3pm snapmirror will kick off as soon as the 2pm snapmirror finishes, at 3:10pm. Now say the 2pm snapmirror takes 130mins. A snapmirror will kick off at 4:10, and assuming it finishes in 30mins, then the system will be idle from 4:40 until 5pm which is when the 5pm snapmirror kicks off.
This is based purely on the snapmirror.conf schedule.
From: tmac <tmacmd@gmail.commailto:tmacmd@gmail.com> Date: Wed, 23 Mar 2011 10:21:23 -0700 To: Timothy Hollingworth <thollingsworth@EPLUS.commailto:thollingsworth@EPLUS.com> Cc: "toasters@mathworks.commailto:toasters@mathworks.com" <toasters@mathworks.commailto:toasters@mathworks.com> Subject: Re: What if SnapMirrror Cannot Keep Up
The current snapmirror will finish and then pick up again when the next scheduled transfer is supposed to happen.
i.e.: mirror takes from 2pm-310pm (maybe due to a slow wan). If the schedule is for every hour, then the 3pm will be skipped and it will resume at 4pm
You can always look to silverpeak or riverbed to help speed up transfers over a WAN.
--tmac Tim McCarthy Principal Consultant
RedHat Certified Engineer 804006984323821 (RHEL4) 805007643429572 (RHEL5)
On Wed, Mar 23, 2011 at 12:48 PM, Timothy Hollingworth <thollingsworth@eplus.commailto:thollingsworth@eplus.com> wrote: So if a source/destination pair is doing a snapmirror update and the current update is not complete before a new update is requested, what is the behavior? Does it queue the second snapmirror update and just update it when the first completes?
I understand the behavior when updates are done by the scheduler on the array itself as per snapmirror.conf. In this case it queues the updates but only to a maximum of three.
"If an update is in progress when another is scheduled to occur, SnapMirror starts another transfer as soon as the transfer is complete. However, if three updates pass while the current transfer is in progress, SnapMirror does only one more update; it does not go back and run updates that have been made obsolete by those scheduled later."
But I'm not talking updates initiated by the scheduler on the array itself.
I'm really asking about something like SME performing a backup and requesting an update. The snapmirror update here is functionally equivalent to issuing a snapmirror update command manually. Suppose the mirror does not complete before the next backup and subsequent update request is made (or snapmirror update command issued manually). What if the rate of data change exceeds the ability of network to complete the mirror or if the WAN link to the DR site is just too darn slow? Do the updates queue on the destination and snapshots build up on the source indefinitely? Or do manual or snapmanager initiated updates follow the "queue to three and then give up" rule above?
Anyone know?
Timothy L. Hollingworth Sr. Network Engineer ePlus Technology, inc. 511 Davis Drive Suite 350 Morrisville, NC 27560 678.462.6698tel:678.462.6698 (Direct/Cell) thollingworth@eplus.commailto:thollingworth@eplus.com
www.eplus.comhttp://www.eplus.com
The information contained in this electronic transmission and any attachments hereto may be considered proprietary and confidential. Unauthorized distribution of this material to anyone other than the addressed is prohibited. Any disclosure, distribution or use of this transmission for any reason other than their intended purpose is prohibited.
I believe the behavior will be the same as what you see from using snapmirror.conf as SME tells snapdrive to tell the destination controller (via API call) to trigger an update. So, in all reality, the actual snapmirror update work is still done by the destination controller.
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-----Original Message----- From: owner-toasters@mathworks.com [mailto:owner-toasters@mathworks.com] On Behalf Of Timothy Hollingworth Sent: Wednesday, March 23, 2011 12:49 PM To: 'toasters@mathworks.com' Subject: What if SnapMirrror Cannot Keep Up
So if a source/destination pair is doing a snapmirror update and the current update is not complete before a new update is requested, what is the behavior? Does it queue the second snapmirror update and just update it when the first completes?
I understand the behavior when updates are done by the scheduler on the array itself as per snapmirror.conf. In this case it queues the updates but only to a maximum of three.
"If an update is in progress when another is scheduled to occur, SnapMirror starts another transfer as soon as the transfer is complete. However, if three updates pass while the current transfer is in progress, SnapMirror does only one more update; it does not go back and run updates that have been made obsolete by those scheduled later."
But I'm not talking updates initiated by the scheduler on the array itself.
I'm really asking about something like SME performing a backup and requesting an update. The snapmirror update here is functionally equivalent to issuing a snapmirror update command manually. Suppose the mirror does not complete before the next backup and subsequent update request is made (or snapmirror update command issued manually). What if the rate of data change exceeds the ability of network to complete the mirror or if the WAN link to the DR site is just too darn slow? Do the updates queue on the destination and snapshots build up on the source indefinitely? Or do manual or snapmanager initiated updates follow the "queue to three and then give up" rule above?
Anyone know?
Timothy L. Hollingworth Sr. Network Engineer ePlus Technology, inc. 511 Davis Drive Suite 350 Morrisville, NC 27560 678.462.6698 (Direct/Cell) thollingworth@eplus.com www.eplus.com
The information contained in this electronic transmission and any attachments hereto may be considered proprietary and confidential. Unauthorized distribution of this material to anyone other than the addressed is prohibited. Any disclosure, distribution or use of this transmission for any reason other than their intended purpose is prohibited.
It will depend on the application requesting the update.
As you say, suppose SnapManager for Exchange initiates one update, that update starts, and SME subsequently requests a new update before the first one completes. The controller will fail the request, saying the mirror is not in an idle state. Now it's up to SME whether it wants to wait and retry or simply give up.
I don't know the SME behavior off the top of my head. Protection Manager will wait up to an hour before giving up. Other applications may behave differently.
-- Pete Smoot, NetApp
-----Original Message----- From: Timothy Hollingworth [mailto:thollingsworth@EPLUS.com] Sent: Wednesday, March 23, 2011 9:49 AM To: 'toasters@mathworks.com' Subject: What if SnapMirrror Cannot Keep Up
So if a source/destination pair is doing a snapmirror update and the current update is not complete before a new update is requested, what is the behavior? Does it queue the second snapmirror update and just update it when the first completes?
I understand the behavior when updates are done by the scheduler on the array itself as per snapmirror.conf. In this case it queues the updates but only to a maximum of three.
"If an update is in progress when another is scheduled to occur, SnapMirror starts another transfer as soon as the transfer is complete. However, if three updates pass while the current transfer is in progress, SnapMirror does only one more update; it does not go back and run updates that have been made obsolete by those scheduled later."
But I'm not talking updates initiated by the scheduler on the array itself.
I'm really asking about something like SME performing a backup and requesting an update. The snapmirror update here is functionally equivalent to issuing a snapmirror update command manually. Suppose the mirror does not complete before the next backup and subsequent update request is made (or snapmirror update command issued manually). What if the rate of data change exceeds the ability of network to complete the mirror or if the WAN link to the DR site is just too darn slow? Do the updates queue on the destination and snapshots build up on the source indefinitely? Or do manual or snapmanager initiated updates follow the "queue to three and then give up" rule above?
Anyone know?
Timothy L. Hollingworth Sr. Network Engineer ePlus Technology, inc. 511 Davis Drive Suite 350 Morrisville, NC 27560 678.462.6698 (Direct/Cell) thollingworth@eplus.com
www.eplus.com
The information contained in this electronic transmission and any attachments hereto may be considered proprietary and confidential. Unauthorized distribution of this material to anyone other than the addressed is prohibited. Any disclosure, distribution or use of this transmission for any reason other than their intended purpose is prohibited.
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George T Chen -
Holland, William L -
Smoot, Pete -
Timothy Hollingworth -
tmac