Benefits of moving out from XP256

[Ninad_1]

Hi,

We have a setup where the storage used is a XP256 array using a mixed of 36 GB and 72 GB disks, with all arrays configured as RAID1. The used space is reaching the full array capacity in near future, hence we need to migrate out of the XP256. We also have a XP1024 array connected to the servers which we are thinking of using to migrate off XP256. Can anyone tell me
1. Will there be any performance benefit/degradation from moving to the XP1024 - what will the benefits/problems be ?
2. What are the benefits of XP1024 over XP256 ?
3. If we are planning to configure RAID5 on the XP1024 - will there be any performance benefit/degradation - what will it be ?

Thanks,
Ninad

[Chan 007]

Ninad,

Your Xp256 is limited on cache that you can dedicate into cacheLUN as it holds only 16GB while the XP1024 has 64GB.

Performance will be better with 64GB of cache.

This is an issue, as the CacheLUN is mirrored as with any writeable memory on the XP.

Therefore, if you have 2 Redo Log Groups, with 2 Members per Group and each Log file is 500Mb, then you would need (500Mb Log File * 2 Members * 2 Groups * Mirror Cache) = (500 * 2 * 2 * 2) = 4Gb of memory must be assigned to the CacheLUN. (I got this long back from one of ITRC's post and copied to my reference in my desktop - I have not idea whose this was, but I agree to this and keep such for my reference - So thank him too)

256 Casestudy - http://www.hp.com/products1/evolution/e3000/case_studies/dfds.html

1024 Info
http://www.hp.ca/products/static/storage/arraysystems/da1024.php

You can use more number of disks in 1024 when compared with 256.

Performance wise 1024 will be better then 256. for the above reasons.

Migrating from 256 to 1024 is better as 256 are bit old and it is a wise idea to do so.

Hope you are fine with this.

Chan

[Ninad_1]

Hi Chan,

So apart from scalability is there mo other benefit ? What about the FC disks - I understand that XP256 hosts SCSI disks whereas XP1024 hosts FC disks. Is there benefit in this ? any other performance benefits of XP1024 over XP256 ? IOPS etc ? I dont know the metrics to compare so request you to suggest and guide Please.

Thanks,
Ninad

[Alzhy]

If the machines using the XP256 are a bit dated (say older rp's) and older HBAs - then moving to XP1024 will yield marginal performance boosts to your apps.

XP1024's benfits are of course scalability (more concurrent server connections) and theorethically more IOPS (due to Fibre Channel disks).

In the 6+ years we've been using Hitachi Array for general Database srorage, we've really never noticed any difference between RAID5 or RAID10 array group configurations. This is possibly due to the need (always) for host based striping of these already RAIDed luns. However, we always keep our archive/redo logs on simple volumes out of RAID10 array groups.

Hope this helps..

[Chan 007]

Ninad,

As already mentioned in my prev statement,

Performance depends on the LUN Cache too. The mroe you have the more your system/IO write can use,

Also performance depends on various factors,

e.g. as Nelson stated you due to FC disks has more IOPS.

Also it depends on how u ihave implemented, e.g

1. the smaller the disk size the better the performance.

2. theoritically the 1024 has deticated processors for each FC port

3. you must implement load balancing by using all FC ports

4.In olden days when you use you database using RAW partitioning with RIAD10 will yield a better performance, you nowadays even gaints like Oracle suggest to go for the LV based DB and hotbackup, etc. So nowadays no issue with RAID5 and RAID10. Only it was benefitting older versions like 7.x of Oracle.

Cheers
Chan

[Ninad_1]

Can anyone tell me some numbers for comparison of IOPS between XP256 and XP1024 ? Also what is the relation between a disk speen (rpm) and IOPS and throughput ?

Thanks,
Ninad

[Chan 007 · Accepted solution]

Ninad,

Disk RPM - is limited to each disks, say one with 18 GB will be 10000 while other with 36 GB will be 11000 or so. This will be decided when you buy a SAN/NAS.

IPOS - is a calculation derived from factors, for e.g if you have a RAID5 with 10 Raid Groups using the SAN multiplied with the IPOS of each disk, (e.g 5*10=50) 50 Disks multiplied with IOPS of each disk will be (50 * 100(Random IOPS) = 5000 IOPS)

Throughput - is your SCSI/FC factor into number of FC/SCSI ports connected to number of Hosts.
e.g if you 4 Disk trays then multiply with MB/s of that channel SCSI = 30MB/s
4 * 30 = 148 MB/s is what your full throught put.

These r just examples not accutare measures.

Chan