Hello Steve, From the NOW site. Solution ID: ntapcs753 Title: Frequently asked questions on Zoned and Block Checksums - NetApp Filer

In short is says that you can mix them but BCS will not be able to act as a spare (in you case you need an ZCS as a spare or will suffer degraded mode if a drive fails.

Q. Can I add a BCS disk to an existing volume group which is currently using zoned checksums? A. Yes, they can all be added but cannot all be used as spares. With the BCS checksum format, 18 GB and 72 GB drives, can be added to a current ZCS volume as a spare in a ZCS or BCS raid group. However a 36 GB BCS drive cannot be used as a spare for a 36 GB ZCS dirve. Note also, that no Zoned Checksum disk can be used as a replacement for a BCS checksum formatted disk.

Note the following exception: Q. Are the FC9 and DS14 34 GB disks identical in size and block capacity A. The 36 GB BCS formatted disk CANNOT be used as a replacement spare disk for the 36 GB Zoned Checksum disk because the 36 GB BCS disk right sizes to 34 GB and the 36 GB Zoned Checksum disk right sizes to 34.5 GB, and, therefore, does not have the same storage capacity.

Q. Will I still get the performance boost from the BCS disk when it is part of a ZCS volume? A. No. Checksums are not stored in the extra 64 bits of the BCS (520B/sector) disk blocks; therefore, the volume still uses either ZCS or, for pre-Data ONTAP 6.0, no checksums at all.

Q. Can a volume have more than one checksum style? A. The checksum style applies to the entire volume. You cannot have a volume with both checksum styles.

Thank you Michael A Schipp ASI Solutions IT LAN/WAN Administrator Phone : 02 9384 8095 Mobile : 0402 907 928 E-Mail : mschipp@asi.com.au Visit us at http://www.asi.com.au

-----Original Message----- From: steve@hq.newdream.net [mailto:steve@hq.newdream.net] Sent: Friday, 14 March 2003 1:12 PM To: toasters@mathworks.com Subject: mixing BCS and ZCS in the same volume

Is it bad to mix BCS and ZCS drives in the same volume? A person from a reputable Network Appliance supply company told me that this will probably most definitely lead to data corruption.

Please read below, I know its a lot of information but it should be useful for someone to give me a straight answer.

before we just had one FC9 shelf of seven 36GB ZCS disks on our F740 filer

slot 8: Fibre Channel Host Adapter 8 (Qlogic 2100 rev. 3, 32-bit, L-port, <UP>) 0: SEAGATE ST136403FC NA11 34.5GB 512B/sect 1: SEAGATE ST136403FC NA11 34.5GB 512B/sect 2: SEAGATE ST136403FC NA11 34.5GB 512B/sect 3: SEAGATE ST136403FC NA11 34.5GB 512B/sect 4: SEAGATE ST136403FC NA11 34.5GB 512B/sect 5: SEAGATE ST136403FC NA11 34.5GB 512B/sect 6: SEAGATE ST136403FC NA11 34.5GB 512B/sect

now we have another FC9 shelf of 36GB BCS disks but the sizes don't match

slot 8: Fibre Channel Host Adapter 8 (Qlogic 2100 rev. 3, 32-bit, L-port, <UP>) 0: SEAGATE ST136403FC NA11 34.5GB 512B/sect 1: SEAGATE ST136403FC NA11 34.5GB 512B/sect 2: SEAGATE ST136403FC NA11 34.5GB 512B/sect 3: SEAGATE ST136403FC NA11 34.5GB 512B/sect 4: SEAGATE ST136403FC NA11 34.5GB 512B/sect 5: SEAGATE ST136403FC NA11 34.5GB 512B/sect 6: SEAGATE ST136403FC NA11 34.5GB 512B/sect 8: NETAPP X231_ST336704FC NA32 34.0GB 520B/sect 9: NETAPP X231_ST336704FC NA32 34.0GB 520B/sect 10: NETAPP X231_ST336704FC NA32 34.0GB 520B/sect 11: NETAPP X231_ST336704FC NA32 34.0GB 520B/sect 12: NETAPP X231_ST336704FC NA32 34.0GB 520B/sect 13: NETAPP X231_ST336704FC NA32 34.0GB 520B/sect

Before we added the second shelf I had it setup very nicely with a boot volume of 2 disks, data volume of 4 disks (w/one spare) and raid group size=7.

Volume boot (online, normal) (zoned checksums) Plex /boot/plex0 (online, normal, active) RAID group /boot/plex0/rg0 (normal)

RAID Disk Device HA SHELF BAY CHAN Used (MB/blks) Phys (MB/blks) --------- ------------ --------------- ---- -------------- -------------- parity 8.0 8 0 0 FC:A 34500/70656000 34732/71132960 data 8.1 8 0 1 FC:A 34500/70656000 34732/71132960

Volume saggy (online, normal) (zoned checksums) Plex /saggy/plex0 (online, normal, active) RAID group /saggy/plex0/rg0 (normal)

RAID Disk Device HA SHELF BAY CHAN Used (MB/blks) Phys (MB/blks) --------- ------------ --------------- ---- -------------- -------------- parity 8.2 8 0 2 FC:A 34500/70656000 34732/71132960 data 8.3 8 0 3 FC:A 34500/70656000 34732/71132960 data 8.4 8 0 4 FC:A 34500/70656000 34732/71132960 data 8.5 8 0 5 FC:A 34500/70656000 34732/71132960

Then a person with very little experience (my boss) added another shelf to the data volume but without first checking the types of disks he was adding, etc. He added NETAPP X231 (BCS) disks to this ZCS voume. These are block checksum disks of a different physical specs. Now it looks like this.

Volume saggy (online, normal) (zoned checksums) Plex /saggy/plex0 (online, normal, active) RAID group /saggy/plex0/rg0 (normal)

RAID Disk Device HA SHELF BAY CHAN Used (MB/blks) Phys (MB/blks) --------- ------------ --------------- ---- -------------- -------------- parity 8.2 8 0 2 FC:A 34500/70656000 34732/71132960 data 8.3 8 0 3 FC:A 34500/70656000 34732/71132960 data 8.4 8 0 4 FC:A 34500/70656000 34732/71132960 data 8.5 8 0 5 FC:A 34500/70656000 34732/71132960 data 8.6 8 0 6 FC:A 34500/70656000 34732/71132960 data 8.8 8 1 0 FC:A 34000/69632000 34190/70022840 data 8.9 8 1 1 FC:A 34000/69632000 34190/70022840

RAID group /saggy/plex0/rg1 (normal)

RAID Disk Device HA SHELF BAY CHAN Used (MB/blks) Phys (MB/blks) --------- ------------ --------------- ---- -------------- -------------- parity 8.10 8 1 2 FC:A 34000/69632000 34190/70022840 data 8.11 8 1 3 FC:A 34000/69632000 34190/70022840 data 8.12 8 1 4 FC:A 34000/69632000 34190/70022840 data 8.13 8 1 5 FC:A 34000/69632000 34190/70022840

Spare disks

RAID Disk Device HA SHELF BAY CHAN Used (MB/blks) Phys (MB/blks) --------- ------------ --------------- ---- -------------- -------------- Spare disks for block or zoned checksum volumes spare 8.14 8 1 6 FC:A 34000/69632000 34190/70022840

The spare is not even good enough if one of the ZCS drives fail!

Please let me how bad this is. Thanks!

Steve

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