Transactional logging and disks
Category
For the record (as I have been asked about this a lot recently).
Transactional logging is great. Implemented correctly, you can gain about 10% disk performance on your domino server. Now what is implemented right? Placing your transactional logs on a separate drive to the data directory (or any directory links). A separate drive is is a seperate physical disk or disk array - with different controllers/spindles. IE Separate.
In relation to a SAN - yes you can put transactional logs on a SAN, but only if you have implemented in the same manner. This usually costs a lot of money (separate drive area/disks/controllers/spindles/LUN). If your blades come with a local array (raid 1 array) use them for your transactional logs and SAN boot them instead. Sometimes, the Domino administrator is not the SAN administrator aswell - and you may need to ensure that if you have Trnslog running on the SAN, that it is done in this manner.
So, unless implemented properly I recommend that the transactional log files are on local drives. I have many scars from SANs!
For the record (as I have been asked about this a lot recently).
Transactional logging is great. Implemented correctly, you can gain about 10% disk performance on your domino server. Now what is implemented right? Placing your transactional logs on a separate drive to the data directory (or any directory links). A separate drive is is a seperate physical disk or disk array - with different controllers/spindles. IE Separate.
In relation to a SAN - yes you can put transactional logs on a SAN, but only if you have implemented in the same manner. This usually costs a lot of money (separate drive area/disks/controllers/spindles/LUN). If your blades come with a local array (raid 1 array) use them for your transactional logs and SAN boot them instead. Sometimes, the Domino administrator is not the SAN administrator aswell - and you may need to ensure that if you have Trnslog running on the SAN, that it is done in this manner.
So, unless implemented properly I recommend that the transactional log files are on local drives. I have many scars from SANs!
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Comments
I've measured also SAN performance using a self-written C++ program: I got like 3GB/s on a SAN disk, and only 1GB/s on a physical internal SAS disk. The huge cache of the SAN was of course relevant.
Posted by Mika Heinonen At 22:51:03 On 13/02/2008 | - Website - |
Paul, by "SAN boot them", do you mean install the OS on the SAN?
Where do you put the PageFile? Doesn't that need to stay on the physical internal disk as well?
I'm really hoping to avoid SAN scars myself here in the near future.
Thank you.
Posted by Scott Stewart At 04:27:23 On 14/02/2008 | - Website - |
I Usually use a four spindle (4*72GB 15k) RAID1E (I use IBM) for Transaction logs and a similar setup for the ViewUpdates volume.
I also tune the Stripe Unit Sizes/Stripe Size and the number of spindles to match what's optimal for Domino on the Datavolume (Raid5)
Posted by Dag Kvello At 12:47:51 On 14/02/2008 | - Website - |