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VA7100 in RAID 5 disc space management

Occasional Visitor

VA7100 in RAID 5 disc space management

We have a system with a VA7100 in RAID 5 (with 5 disc of 18Go Each, one
of which is in Hot stare) normally it remain to us 54Go (3 discs) for
data storage but we have only 30Go of free space. Iâ d like to ask the following questions :

1- In general on a system of this type (VA7100 in RAID 5 with 5 discs installed) which percentage of disk space is reserved by VA. There is a means to reduce this percentage ?

2 - To add new disc with VA in RAID 5 how to make, without disturbing the system and the
data which already exists.

3- If we decide to add new discs, the proportionality would remain the
same one (almost 50% of space available is reserved by VA7100 for its
own use) ?.

Bernhard Mueller
Honored Contributor

Re: VA7100 in RAID 5 disc space management


the VA7100 does not use RAID5. You can select (but not switch to and back) RAID 0/1 and AUTORAID mode. Usually you use autoraid.

This means that if necessary data is moved from RAID 0/1 to RAID5DP to fully use the capacity.

Hot spare mode can be set to automatic, largest disk or largest 2 disks. Usually you use largest disk. The VA uses "active hot spare", i.e. it reserves some space on *all* disks to compensate the possible failure of the largest disk.

Also it *always* keeps the 10 percent top used data in RAID 0/1.

That is why it is difficult to exactly estimate what net capacity will be available with so and so many xGB disks.

Hope the above covers Q1.

Q3: Concluding from the above, your percentage of available net space will somewhat improve when you add more disks (however if you add only *one* larger disk it will go down because of hot spare mode "largest disk"....)

Q2: you can add disks online without taking the VA or any host down. Recommendations *before* you add disks are:
make sure everything is in "good" state (armdsp -a); if newer controller firmware is available upgrade controller fw first; if possible add same size disks; upgrade firmware of existing disks if newer version is available.

Occasional Visitor

Re: VA7100 in RAID 5 disc space management

thank you for your response Bernhard.