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Using SC volumes as WHOLE DRIVE vs as PARTITIONS?
While debuging an issue we encountered, a support engineer sent me a document on how to use SC with RHEL 7.
On page 8, it says:
Partitions (and partition tables) are not required for volumes other than the boot volume; use SC Series volumes as whole drives. This leverages the native strengths of the SC Series wide striping of volumes across all disks in the tier where the volume is provisioned.
This seems to have nothing to do without our problem but I did notice that our previous exercise didn't really conform with this. We created a partition on mpathc rather than using it as a whole drive, as opposed to the newly created mpathd. Here's an output of lsblk:
sdg 8:96 0 28T 0 disk
└─mpathc 253:2 0 28T 0 mpath
└─mpathc1 253:3 0 28T 0 part /bak
sdh 8:112 0 28T 0 disk
└─mpathc 253:2 0 28T 0 mpath
└─mpathc1 253:3 0 28T 0 part /bak
sdi 8:128 0 100T 0 disk
└─mpathd 253:6 0 100T 0 mpath /work3
sdj 8:144 0 100T 0 disk
└─mpathd 253:6 0 100T 0 mpath /work3
My question is, what and how much influence is this deviation from suggested handling on mpathc or /bak gonna have?
Thanks.
DELL-Bob Mi
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June 22nd, 2019 07:00
Hello 5X5CX62,
This should have very little influence on your other partitions. The SC presents data at a block level to the operating system of whatever host is connected. The host then determines how that space is used. For example, you can present a 4 TB Volume to any host, and at the host level set that space up as 2 - 2 TB partitions, or 4 - 1 TB partitions. Some previous operating systems were unable to handle partitions larger than 2 TB which made it necessary to segment a 4 TB Volume at the host level. In many instances that is no longer necessary.
5X5CX62
20 Posts
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June 22nd, 2019 12:00
Hi Bob,
Thanks for the reply. Could you also elaborate a bit more ragarding the statement "This leverages the native strengths of the SC Series wide striping of volumes across all disks in the tier where the volume is provisioned."
What's the difference if a volume is used as a whole drive versus being divided into several partitions at system level. We are using RHEL/CENTOS btw.
Wade
DELL-Bob Mi
230 Posts
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June 25th, 2019 10:00
Hello 5X5CX62,
By default a SC Series stripes data across multiple disks versus a normal server which only uses a single disk. This give you better performance and redundancy. This is what that statement is referring to.
There really is no difference in provisioning a volume as a single partition versus dividing into several partitions at system level. This is a choice to be determined by the server administrator.