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PowerVault ME4024 SSD read-cache disk group
We recently acquired a PowerVault ME4024, with a mix of flash and 10k drives. We bought some SSDs to use them as storage and some (2x480GB) to create a SSD Cache.
I have created a read-cache disk group with these two drives but I'm not sure I have configured them correctly:
Pool A
- 8 SSDs in two RAID10 disk groups
Pool B
- 2 SSDs in a RAID0 read-cache disk group
- 8 10 SAS 10k disks in two RAID5 disk groups
I created the disks groups and some volumes, but I want to be sure the 10K disk groups are being optimized by the read-cache disk group.
Can you help me?
DELL-Sam L
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November 13th, 2018 08:00
Hello Markman12-,
The following is found on page 88 of the administrator guide. https://topics-cdn.dell.com/pdf/powervault-me4024_administrator-guide_en-us.pdf
“A read-cache disk group is a special type of a virtual disk group that is used to cache virtual pages to improve read performance. Read cache does not add to the overall capacity of the pool to which it has been added. You can add or remove it from the pool without any adverse effect on the volumes and their data for the pool, other than to impact the read-access performance.
If your system uses SSDs, you can create read-cache disk groups for virtual pools if you do not have any virtual disk groups for the pool that are comprised of SSDs. Virtual pools cannot contain both read-cache and a Performance tier.
Only a single read-cache disk group may exist within a pool. Increasing the size of read cache within a pool requires the user to remove the read-cache disk group, and then re-add a larger read-cache disk group. It is possible to have a read-cache disk group that consists of one or two disks with a non-fault tolerant RAID level. “
Based on the way you have configured your disk groups & pools your setup follows the setup for SSD read-cache.
Please let us know if you have any other questions.
Markman12-
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November 13th, 2018 11:00
I followed those steps you comment, thanks for your reply, but I had the feeling I was missing something, because there is no setting where I can instruct the disk groups or volumes to force the use of the SSD cache.
Thank you.
DMONTAGNA
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July 16th, 2019 06:00