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Backup to Disk Design Question
Hello,
CX and Legato Networker for Backup to Disk:
How to expand my Backup to Disk Target in the best way:
MetaLUNs for expansion (striped or concatenated) or create a additional File-Device for each Raid-Group(LUN)?
What are the considerations?
thx.
regards mpi
CX and Legato Networker for Backup to Disk:
How to expand my Backup to Disk Target in the best way:
MetaLUNs for expansion (striped or concatenated) or create a additional File-Device for each Raid-Group(LUN)?
What are the considerations?
thx.
regards mpi
GlenH
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June 27th, 2007 15:00
OK, so here's some suggestions.
1. with B2D on ATA, the general recommendation is to make 1 LUN that uses the entire raid group. If you decide to make more than 1, make sure that all of the LUN's in each ATA raid group are owned by the same SP as the ata drives are not dual ported like the FC drives and having spa and spb access a drive simultaneously will reduce the performance of all of the LUN's on that raid group. Raid 3 is a good choice for sequential workloads - just remember that r3 can only be configured with 5 drives (4+1) or 9 drives (8+1).
2. As you have 2 raid groups, the best option is to present 2 LUN's to the server (1 from each raid group) and have one owned by SPA and the other by SPB. This way you are sharing the load across the SP's and the FC ports. Alternatively you could make a meta lun using both raid groups, but in that case only 1 sp will be active and this will unbalance your array SP's.
3. As long as you're OK with having 2x filesystemsvthen the 2 LUN option is the best way to go. To expand these later on, you would need to get another 2x raid groups (2 because you need 1 per SP) , and then create meta lun's to grow the existing LUN's into the new raid groups, keeping to the rule of all LUN's in each raid group are owned by the same SP...
4. Whether it's windows or linux, remember to set the partition offset to align your partitions correctly.
5. Finally, although you can expand LUN's, I would suggest if you need more throughput and are considering expanding a LUN into another raid group, don't make a single LUN larger than 2TB or so as you will not necessarily get more performance out of it. The server OS can only queue so many SCSI requests to a disk device and you will find that you are not making the best use of the array's capability when you make a single LUN very large. Presenting more smaller LUN's will serve you better, although that is a little awkward when using basic disks... If you're happy with the throughput you are getting and just want more space, then go ahead and make it bigger (as long as the server OS and FS can support >2TB devices)
Hope that helps,
Glen.
ble1
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June 26th, 2007 04:00
https://powerlink.emc.com/nsepn/webapps/btg548664833igtcuup4826/km/live1/en_US/Offering_Technical/White_Paper/H2509_bu_to_disk_gde_networker_wp_ldv.pdf?mtcs=ZXZlbnRUeXBlPUttQ2xpY2tDb250ZW50RXZlbnQsZG9jdW1lbnRJZD0wOTAxNDA2NjgwMWYwMjM1LGRvY3VtZW50VHlwZT1wZGYsbmF2ZU5vZGU9MGIwMTQwNjY4MDFhYTY3MA__
mpi2
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June 26th, 2007 04:00
I already read this paper but I didn't find any considerations for my "special" question.
ble1
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June 26th, 2007 04:00
GlenH
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June 26th, 2007 15:00
Some of the considerations are:
1. Balancing the workload across the clariion SP's.
2. Keeping all ATA LUN's in a raid group on the same SP
3. Making sure you don't have such a big device presented to the server that you can't send enough scsi requests to it to keep it busy
4. If the OS / LVM can make use of an expanded LUN.
To give you a reasonable answer, I need to know the following:
1. Are you using ATA or FC drives
2. The RAID type and # of RAID groups
3. Which Operating system
4. Which volume manager
5. The current size and number of your existing LUN's
Regards,
Glen.
mpi2
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June 27th, 2007 01:00
Thank you for your response.
My question was not carefully worded.
I'm going to design a B2D solution so I don't have it yet.
But to think of the future I don't want to block a good expansion design with a bad implementation know.
1. We're want to use ATA drives. (500GB)
2. 2 x 4+1 R3 Raidgroups for the beginning
3. Linux or Windows as Backupserver
4. Standard-OS-VM with ext3 or NTFS (basic) (so FS expansion should not be a show-stopper)
Thank you for further inputs!
best regards
mpi
mpi2
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June 28th, 2007 03:00
Thank you for your response.
The expansion strategy sounds excellent.
I will make use of it!
best regards
MPI