February 13, 2018 at 10:23 am
We are looking to upgrade to a solid state drives only server. It will be raided. Does it make any sense to create logical drives to separate the OS, data, logs and tempdb (as we do with spinning drives) or should we just go for a single logical drive given there are no moving parts?
February 13, 2018 at 3:07 pm
Although we can find reasons to do or not to do it, I suggest you create different logical drives.
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February 13, 2018 at 9:43 pm
Alexander Zhang - Tuesday, February 13, 2018 3:07 PMAlthough we can find reasons to do or not to do it, I suggest you create different logical drives.
Why? Making a recommendation with no reasons offered isn't very useful to someone.
--Jeff Moden
Change is inevitable... Change for the better is not.
March 3, 2018 at 7:43 am
rchantler - Tuesday, February 13, 2018 10:23 AMWe are looking to upgrade to a solid state drives only server. It will be raided. Does it make any sense to create logical drives to separate the OS, data, logs and tempdb (as we do with spinning drives) or should we just go for a single logical drive given there are no moving parts?
If the physical disk (RAID or single disk) is just one, having multiple logical drives won't make a different but slow, not much (probably won't even notice since it's SSD), things down.
It makes sense to have multiple disks if each logical disk has a physical of it's own.
You can create the multiple logical disks if you want to "separate" things (OS and SQL, tempdb, data, log - 4 logical disks) but in your case is just for keeping things "tidy"...
March 5, 2018 at 10:36 am
Thanks PiMané.
Re the logical drives, I think with one platter I'd just organize the various pieces into folders. That way if we add a drive the space will become available to any/all folders; there won't be a need to manage space on separate drives, i.e. space on C: vs space on D:, etc.
A more interesting question is probably how to organize say 16 solid state drives on the server. One large physical drive, or a physical C:, D:, E: and F: ? I.e. separate physical RAID arrays for system, data, logs and tempdb or one large raid array and folders for organization?
In my mind it would come down to speed, i.e. is there a speed advantage to having separate RAID versus one big RAID when all the drives are solid state?
March 5, 2018 at 10:48 am
rchantler - Monday, March 5, 2018 10:36 AMThanks PiMané.
Re the logical drives, I think with one platter I'd just organize the various pieces into folders. That way if we add a drive the space will become available to any/all folders; there won't be a need to manage space on separate drives, i.e. space on C: vs space on D:, etc.A more interesting question is probably how to organize say 16 solid state drives on the server. One large physical drive, or a physical C:, D:, E: and F: ? I.e. separate physical RAID arrays for system, data, logs and tempdb or one large raid array and folders for organization?
In my mind it would come down to speed, i.e. is there a speed advantage to having separate RAID versus one big RAID when all the drives are solid state?
Separate physical disks is always better...
With 16 disks you can have 4 physical RAID 10 (4 disks per RAID) partitions that is the best system for databases, but since SSDs are extremely fast I would go with RAID 1 (2 disks) for OS and SQL Server installation, RAID 1 (2 disks) for tempdb, if you tempdb is not very intensive writing, and RAID 10 (with 8 disks) for database files.
Having just one big RAID 10 with 16 disks won't make much of a difference in performance but with separate RAID you can "keep the house clean"... But either way you are good...
March 5, 2018 at 1:40 pm
In my mind the house can be kept clean via a sensible directory structure.
If I separate the drives into multiple raid arrays each array will have a space limitation and each one will need to be managed. If I have only 1 large array, I can add a disk whenever anything (logs, data, etc.) needs space. So, its easier and more efficient from a space management perspective to have only 1 array.
However, if there are performance advantages to having multiple arrays that could win the day, i.e. moving toward multiple physical arrays, like we would have done with spinning disks. I just don't know how performance is affected by creating multiple raid arrays versus 1 raid array. I would guess it works similar with spinning drives but maybe not because of the speed of the SSDs.
March 5, 2018 at 1:43 pm
I have also wondered on SSD why would there be a need to separate out data, logs and TEMPDB onto different drives. I originally thought that was for spinning drives to spread out hot spots.
The trouble I have in having a data drive, translog drive and a TEMPDB drive is that I have a lot of free space on all three so they all three can grow. SAN people see all of the free space and think I am wasting it. I tell them, trans logs can grow greatly for spike usage. Also, TEMPDB can as well for sorts and rebuild indexes. They simply see it as allocated and not used space.
March 6, 2018 at 10:18 am
Jeff Moden - Tuesday, February 13, 2018 9:43 PMAlexander Zhang - Tuesday, February 13, 2018 3:07 PMAlthough we can find reasons to do or not to do it, I suggest you create different logical drives.Why? Making a recommendation with no reasons offered isn't very useful to someone.
In the company I'm working for, we have thousands of MSSQL instances with different hardware and centralization management tools. The reasons that I suggest we create different logical drives are very simple,
1. It might be helpful to keep them consistent among different instances. Otherwise, it probably brings extra work on tools or maintenance. And I'd like to keep thing as simple as possible.
2. I just like it if it doesn't hurt much:-)
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