Several questions about DELL SC compellent storage expansion

In the past few weeks, I have received some requests about DELL SC storage expansion. Every time I have to do a lot of science popularization on the compatibility of disk expansion cabinets, but even if I talk about it every time, the other party still doesn’t understand. Or people simply don't believe what you say.

This article summarizes some common problems in capacity expansion for the reference of friends in need. For details, you can add wechat at StorageExpert for further discussion and communication.

1. What are the disk expansion cabinets of DELL SC, and what are their characteristics?

From a large perspective, I divide it into three categories of products. One category is the cabinets acquired by DELL very early in the compellent era, Xyratex OneStor, which basically has no capacity expansion, and there are still some used, and often received Disk requirements for this cabinet.

The second type is the expansion cabinet with DELL SCv20XX, SC4020 and SC8000 generation, 6Gb back end, including SC1XX, SC2XX products.

The third category is the expansion cabinet with DELL SCv3XXX, SC5020, SC7020 and SC9000 products of this generation, with a 12Gb back end, including SCv3XX and SC4XX.

For detailed types, refer to the table below:      

12Gb Expansion Enclosure	6 Gb Expansion Enclosure
SC400 Premium 2U, 12 drive slots 3.5" disks	SC200 Premium 2U, 12 drive slots 3.5" disks
SC420 Premium 2U, 24 drive slots 2.5" disks	SC220 Premium 2U, 24 drive slots 2.5" disks
SCv300 Value 2U, 12 drive slots 3.5" disks	SC100 Value for SCv2000 series 2U, 12 drive slots 3.5" disks
SCv320 Value 2U, 24 drive slots 2.5" disks	SC120 Value for SCv2000 series 2U, 24 drive slots 2.5" disks
SC460 Premium 4U or 5U with cable management system, 60 drives slots 3.5" disks	SC280 Premium 5U, 84 drive slots 3.5" disks
SCv360 Value 4U or 5U with cable management system, 60 drives slots 3.5" disks	SC180 Value for SCv2080 5U, 84 drive slots 3.5" disks
Xyratex OneStor This is a very old cabinet acquired by DELL in the era of compellent, which is rarely used, so we won’t discuss it here.

2. 6Gb和12Gb的柜子是否可以混插在一个loop中？

这个答案是YES and NO，就是可以也不可以。说白了就是有条件的。在SCOS版本 7.3之前，是不能混合在一起的，就是两种扩展柜是不同接到一个磁盘loop中的。但是到了7.3版本以后，这两种不同速率的柜子是可以接到一起的。但是，重点来了，我们在做阅读理解的时候however之后一般都是重点，建议把12Gb的柜子接到6Gb的loop上，就是可以把SC420，SC400这些柜子接到SC4020，SCv2XXX上，这样12Gb的后端其实是工作在6Gb上。不要反过来，在SC5020或者SC7020的机器上挂SC200，SC220，SC100，SC120之类的柜子，这样就把原来12Gb的后端整体拉低到了6Gb。

3. 低端设备的柜子（SCv2000和SCv3000）能不能用到高端设备（SC5020/SC7020,...）?

在回答这个问题之前，先要定义一下DELL SC的产品，他把产品分为SCv系列和SC系列，v是vaule的意思，这个产品主要有SCv2000，SCv2020，SCv3000，SCv3020，和这个产品对应的扩展柜有 SC100，SC120，SC160，SC300，SC320，SC360。

其他的产品就是SC的高端产品，对应的扩展柜是SC200,SC220,SC260,SC400,SC420,SC460,SC280等。

简单来说，高端产品可以用value产品的柜子，但反过来不行。举个例子，客户有一台SCv3000产品， 他是可以使用SC400，SC420的柜子的。但是反过来，如果客户有一台SC7020产品，是不支持使用SC300和SC320的柜子的。

其实其他还有咨询如何扩容的，咨询磁盘兼容性的，咨询SAS后端线缆的，这里就不一一说明了，有问题add wechat at StorageExpert.